bcp
In My Opinion
I went to plenty of concerts in my younger days and have used the mens room many times opposed to waiting in line for the ladies room. You know what happens when a woman walks in the mens room? The men make an effort to cover their stuff. I'm certain it's because I don't have a wanker and has nothing to do with sex or sexuality. The same reason my young boys cover themselves around their step sisters but not around other boys.
maybe they thought you were a crossdresser and didnt want to excite you