yeah, that and Bruce getting along with everyone, among other things :I
Bruce has been shown to have friends in Round 1. Even still, he's able to be amicable to people he doesn't talk to often (Like Bucky and Drayden).
You can also see in their conversation at the end of the night, Bruce is standing away from Zander and speaking pretty quietly. Anyone looking on won't be able to tell that they're having a conversation, and if they CAN tell, they're probably too drunk to remember it at this point.