Oh yeah, you missed your chance there. That was definitely a "first move" for him. You should have been cool.
Have you ever seen each other's cocks? If not, go some bar where the urinals don't have partitions. When he goes in to piss, follow him in and stand not at the next urinal but one down from that. If you stand right next to him he'll freak. Continue talking (that's why you had to stand somewhat near him instead of the two farthest ones away from each other). Then notice his cock and compliment him on it in a non-creepy way. "I'll bet the bitches love that!" has worked for me several times. LOL
Anyway, that will help break down the walls. After that start showering with the bathroom door open etc.