Casual Homophobia in Gaming

My regular campaign group met today.  I've written a few other posts about it.  The world has been magic deprived for the last century or so, and it appears that the magic is slowly returning back (in metaplot terms, we have a new GM who has only recently returned to GMing and wants to incorporate the full ruleset slowly).  The campaign has been running since August and today we had our first encounter with monstrous creatures--a phase spider and a land-based decapus.

The dreaded decapus slithered our way.

t today.  We've gotten into a regular groove for every other Sundays.  I'm really enjoying being a player as well and our GM is doing a great job.  I particularly enjoyed encountering the decapus--it was presented without a Bestiary-entry-based description and so it was like trying to figure out an entirely new threat!  I loved it!

I'll skip over the plot points (though I'm happy to share game notes with anyone who's interested), but we had a moment where we were talking about getting the short end of the stick.  And one of the other players made reference to "a dick up the ass."

He knows I'm gay.  I don't believe that he has any problems with it either.  In fact, I doubt that this person thinks of himself as homophobic at all.  I tried to slough it off as a joke while still pointing it out, but it actually left some lingering resentment.

I'm conflicted about how to address this.  Our GM is my college roommate, so I know that I can say anything to him.  And, I know that he'll understand it.  But, I'm not sure that I need to involve him.  I struggle between wondering if I should pull him aside and say something or if I should try and casually hint that this behavior isn't okay.  On the one hand, I think issues related to casual homophobia are best dealt with quickly and concisely.  On the other, no one ever wants to rock the boat.  So, maybe it would be best to try and just let things sort themselves out.

Dear readers, what do you think?  What's the best way to address casual homophobia in gaming?