OKay buddy, first of all disregard what most of the morons are posting - especially the anti-LDS ones, of course they want you to do something you shouldn't!
Two things:
1) Is it a sin?.. probably more "inappropriate" but definitely on dodgy ground.
2) Avoid the "appearance of evil". Think what your mother would say, or the Savior.
Don't get me wrong I'm not saying you are some major evil doer 'cause that would be crazy but the not clothed bodily contact isn't something you should be getting up to. Pray about it - you still feel bad then go tell the Bishop. He is your "judge in Israel" and can set you straight. And hey, that conscience of yours is there for a reason. Next time get out and make space that way. It's too easy to have something meant innocently turn well not innocent.
The fact that it's bugging you shows you have a good heart and want to do your best.
RM