The attorney for the suspect said it was a misunderstanding, saying his client thought he was getting a cheap airline ticket, not a fake one.
The checkpoint had been closed for two weeks due to TSA staffing shortages amid the partial government shutdown.
Authorities accused the 30-year-old Marine of having a live 25mm explosive round in his checked bag at the Palm Springs International Airport.
At Philadelphia International Airport, about 15% of TSA workers called out Monday, according to union officials, a figure that's down from roughly 25% over the weekend.
Weary travelers hope the overdue paychecks will end the hours-long waits in security at several major U.S. airports.
President Trump's executive order on Friday instructed the Department of Homeland Security to pay TSA officers immediately, although it's unclear when the impact of that move will start to be felt at airports.