I don't have a problem with seeing naked girls, (I'm straight though) but I do get that way when I see naked guys, or even just shirtless guys. I feel really uncomfortable any time I see a guy that I feel that I look like, or should look like anyway, and I get incredibly self conscious and the whole 9 yards. So I guess I can relate to you in a way. I'm sure it's not uncommon though. If I see a girl who has a body similar to mine, I'm a bit disgusted and I find it attractive in no way at all. Which is hard because it took me awhile to find feminine hips attractive since I've hated mine for so long.
I'd say it just comes from something deep-rooted of disliking the body you were born with, or being uncomfortable with it, so you might subconsciously see traits of yourself that you dislike in those images.