Yeah, he wasn't actually foolish enough to hand it to them right at the booth. He was taken aside for further questioning since he had already been in the US on a visa waiver within the same calendar year, which pattern-matched border dodging. He was forced* to hand over his wallet early on and the card was clearly there. There's obviously more context, but it's funny that such a minor thing came to be so important -- and sticks in my head 3 years (and one marriage) later.

* Not sure where this fell on the spectrum of 'force', but had he refused, that would presumably have increased suspicion. Damned if you do, etc.