The difference between those two scans -- one triggering an alarm and one not -- will lead to a formal Senate inquiry, Paul (who has been a strong critic of the TSA's pat down policy) told me in the airport.
Paul questioned why the machine would go off once and then not a second time. He said he suspects the equipment is rigged to set off false positives that then allow the TSA to conduct random pat downs without having to pull a passenger aside.
"I think was mine probably random, I doubt I was picked on," he said. "But I would like to know: does the screener have the ability to push the button and randomly get someone to set off a screener?"
His full quote about his suspicions -- and the formal investigation he intends to launch into them:
Some of the people there [TSA officers in Nashville] indicated that some of the reasons the machines may be going off are not because you have something on your body. Because you know every one of us, we're getting rid of everything in our pockets, we're doing all this to try to comply, and then it is a little insulting if it is a random screening. I'd like someone to ask the TSA that question. We're going to go ask them formally, but I'd love if it the media would ask the TSA head, are the machines going off to give screenings, because otherwise they're not very good then if I came back through it 30-40 minutes later and the machine doesn't go off, then my suspicion then is that maybe it is a random screening.
"The buzzer didn't go off [the second time] which means -- I think those machines are pretty sophisticated," Paul continued. "I can't imagine how it's detecting something one minute and not detecting it."
I asked him if he thought the machine had been geared by TSA not to go off when he went through the second time.
"I don't know that," he said.