Then, just like that, she turned on a big smile and worked the room like a pro.
Thanks to this Colorado teenager, America's swim hopes are back on track at the Olympics.
Michael Phelps has yet to win a gold medal, and Ryan Lochte's star has dimmed just a bit. So it was Franklin providing a much-needed boost to swimming's powerhouse nation, coming back less than 14 minutes after swimming a semifinal heat to win the first gold medal of what figures to be a dazzling career.
"Indescribable," the 17-year-old Franklin said after rallying to win the 100-meter backstroke Monday. "I still can't believe that happened. I don't even know what to think. I saw my parents' reaction on the screen and I just started bawling. I can't even think right now."
After finishing up the semis of the 200 freestyle, she hopped out of the pool and headed to the diving well for a quick warmdown. She didn't even have time to make it to the practice pool, not when her bigger event was coming right up.
Even Phelps was amazed at Franklin's stamina, saying he had never done back-to-back races that close together at such a major meet. His quickest turnaround was about a half-hour.
"She's a racer and she knows what to do," Phelps said.
Matt Grevers kept the gold medals coming for the U.S. in rat-a-tat fashion, following up Franklin's win with one of his own in the men's 100 back. For good measure, Nick Thoman made it a 1-2 finish for the red, white and blue.
Rebecca Soni nearly pulled out a third U.S. gold, rallying furiously on the return leg of the 100 breaststroke. But she couldn't quite catch blazing Lithuanian Ruta Meilutyte, a gold medalist at the tender age of 15.
Good thing for the U.S. that Franklin and the other Americans are coming through.
Phelps missed the podium in his 2012 Olympic debut, and Lochte has turned in two straight disappointing performances after opening the games with a dominant win in the 400 individual medley. He finished fourth and off the podium Monday night in the 200 freestyle, which France's Yannick Agnel won by a full body length against a field with gold medalists galore.
On Sunday, Lochte anchored the U.S. in the 4x100 free relay, taking over with a seemingly comfortable lead. But Agnel chased him down on the final leg, giving France the gold.
Now, another defeat.
"I did my best," Lochte said. "I guess sometimes you win, sometimes you lose. I gave it 110 percent. There's probably some things I messed up on, but you live and learn. (Agnel is) a great racer. There's no doubt about it. He's quick and he showed it last night and tonight. I'm happy for him. He did good."
Franklin, who was rattled less than two weeks before the Olympics by the Aurora theater shooting not far from her home, barely advanced from the 200 free semis. She qualified for Tuesday night's final with the eighth-fastest time, but clearly she was saving something for the race that really mattered.
She's still got five more events to go, having started her Olympics with a relay bronze and leaving plenty of time to come away from these games as America's big star in the post-Phelps era.
The winningest Olympian ever plans to retire after these games.
Australia's Emily Seebohm, the top qualifier, led at the turn and was under world-record pace, but Franklin showed a remarkable finishing kick. With her arms whirling and size-13 feet pounding the water, the 6-foot-1 swimmer passed the Aussie in the final 25 meters and lunged toward the wall for a winning time of 58.33 seconds.
She broke into a big smile but was clearly exhausted, her head dropping back against the wall. Seebohm settled for silver in 58.68 and Japan's Aya Terakawa took bronze in 58.83.
"You never know until you see that scoreboard, so I was just going as fast as I could until I got my hand on the wall," Franklin said. "It was 110 percent effort, and all the work paid off."
The 6-foot-8 Grevers pulled off a similar rally on his return lap, winning the 100 back in an Olympic-record 52.16 - the fifth straight games, dating to Atlanta in 1996, that the U.S. men have won the backstroke. Thoman joined his teammate on the medal podium at 52.97, a gold-silver finish they were thinking about all along and reiterated just before the final.
David Marsh, Thoman's coach, brought it up right moments before they went out to the pool, saying "1-2."
Grevers said he and Thoman knew they "weren't jinxing anything," and they were right, though Grevers didn't notice right away that Americans took the top two spots.
"I must be selfish because it took me a good 10 seconds to realize he got second," he quipped. "That's something I should do right away. But when I noticed, that moment became much more special. To know that we can go 1-2 in that event, again really shows the USA's dominance in backstroke right now when we're able to step up."
Japan's Ryosuke Irie was third in 52.97.
"I've been watching the Olympics for as long as I can remember," Thoman said. "The first one I really remember is the '92 Barcelona Games and just watching guys back then. Seeing Lenny Krayzelburg, my idol, and then Aaron Piersol, again my idol, who I got to train with for a little while. Just being able to carry on that tradition, it's a great thing."
Agnel showed that his brilliant swim on the Olympic relay was no fluke. The baby-faced, 6-foot-6 Frenchman did it again in the 200 free, leading from start to finish in perhaps the most star-studded race of these games - even without Phelps, who passed up a chance to defend his Olympic title.
That might have been a good move by Phelps. It was hard to see anyone beating Agnel on this night, as he pulled away to win by a full body length in 1 minute, 43.14 seconds. No one came close to challenging him, and he looked just as strong at the end as he did at the beginning.
"I really didn't expect that time," Agnel said. "I had a race plan in my head, but this is above my expectations and hopes. I'm delighted. It's a childhood dream come true. I had to start quickly over the first 100 meters. I did that. Then I worked on keeping my speed and putting all my guts into the last 50. I don't know what to say. It worked."
French President Francois Hollande came to the mixed zone to congratulate Agnel, shaking his hand warmly in the chaos of reporters and cameras. He was dwarfed by the swimmer, who gave the country its third swimming gold of the games - its most ever.
And there's still five nights to go at the pool.
"Remarkable, two gold medals two nights in a row," Hollande said. "It's a big reward for French swimming, a proud moment for him and encouraging for the whole Olympic team."
South Korea's Park Tae-hwan and China's Sun Yang tied for the silver in 1:44.93. But Lochte, the reigning world champion who seemed poised to have a huge Olympics just 48 hours earlier, faded out of the medals. So did world-record holder Paul Biedermann of Germany.
Soni tried to make it three in a row, but Meilutyte dashed those hopes. Competing for the first time on a major international stage, the 15-year-old showed her strong performances in the prelims and semis were no fluke.
She built a big lead on the outward lap, then held off the 2008 Olympic silver medalist on the return. Meilutyte touched in 1:05.47, while Soni's rally came up eight-hundredths of the second short. Japan took yet another bronze with Satomi Suzuki in 1:06.46.
Meilutyte broke into tears on the medal stand, the enormity of her accomplishment at such a young age finally sinking in. She became the first Lithuanian to win a swimming medal, and took her country's first gold in any sport since a shooting gold in 2004.
"I can't believe it," she said. "It's too much for me. I can't really say anything. It was hard and difficult."
Soni swept the 100 and 200 breaststrokes at last year's world championships, and was hoping to do the same in London. Now, she'll look to defend her title in the 200 breast.
"I'm a little disappointed," she said. "I knew it was going to come down to the last five meters and I wish I had five more meters to get to that finish. It was a great race overall."
Lochte is looking more and more like a swimmer who took on too much of a workload. He's already raced six times in three events covering a total of 1,500 meters over the first three days in London. He has three more events to turn things around, but definitely has the look of a tired swimmer.
If nothing else, it shows just how unbelievable Phelps was when he won a record eight gold medals in 2008.
"To win six of them is a really hard thing to accomplish," Grevers said. "Your body's going to get tired. It's not just a physical strain, it's an emotional strain to try to get up and compete every time."
Phelps didn't have any medal races on this night, but he did advance comfortably through the prelims and semis of the 200 butterfly, going into Tuesday's final with the fourth-best time.
This will be his second attempt at becoming the first male swimmer to win the same individual event at three straight Olympics. He failed in the 400 medley, and Japan's Kosuke Kitajima came up short of the same feat in the 100 breaststroke.
As for Franklin, someone noticed afterward that she wasn't wearing her medal.
She pulled it out of her pocket and marveled, "Isn't it pretty."
Then, she showed her age again. There's still one more year to go at Regis Jesuit High.
"My junior year was awesome," Franklin said. "I can't wait to go back to Regis!"