Lee watched the as John bantered with the other guy about his name. Wedge? Chewbacca? well he really didn't know anything about Earth names but clearly there was more to this conversation then met the eye.
Wedge was obviously playing things cautiously and Lee could understand that, he'd done so too, but Sheppard was more than aware of it also from what Lee could tell. He managed to avoid frowning, he saw no reason to give away that he was aware of what they were doing. He didn't have any call to be particularly wary of the Colonel, the guy had seemed to be fairly straight with him so far.
He was a little bit more leery of the other, given what he'd observed about him initially. So he decided to hold his tongue and observe for a while. Maybe he could learn a bit more about the humans of Earth that way. Besides, that was another thing that bartenders did.