All of the above.
@OP - You sound like a really nice guy that made a small mistake, even an social gaffe, and you were really unlucky to have run into her the same time you did.
I would hope the lesson most people from this is-- check your junk in the bathroom. Adjust your bras and boobs, your crouch, your underwear, your balls... whatever... in the bathroom. If it's REALLY vulgar, a stall.
*edit- I wonder how many of the posters here saying "what the hell, everyone does this" are dudes. I know *some* men that openly check their zipper or adjust their balls in public, but generally most men seem to realize it's probably inappropriate. The OP seemed to realized that it's something to be done with you're alone (hence thinking that no one else was there).
I wouldn't report someone for sexual harassment, but I certainly think it's in poor taste to do it openly. Grabbing yourself in public is just vulgar, even when it's not sexual.