I'm a female IRL, and play a female character etc, but when people use male pronouns I just think it's kind of funny and brush it off. Never took any mind to it, the people I talk to regularly find out sooner or later, and the people who I play with in DF or PF I'm probably only gonna see once so I don't really care. I'm with randoms to get a task done, I don't care if they think I'm a male, female, or anything in between.

This is really the last place where sex should matter, don't take it personally.