I'm in a really good relationship but what does it mean if I still want to be on an adult dating site?

This is such a wierd question, and I feel so strange asking it but I also feel I need to talk to someone about it. I'm in a really great relationship at the moment, with a woman I'm completely in love with (I'm 28, she's 29) and who loves me. She's gorgeous, funny, clever, supportive. Going out just over 7 months, we've booked our first holiday. Catch is, before we started dating I was using an adult dating site called Watchers Web, I flirted and had fun with a few women on there which of course all stopped once I started going out with my girlfriend, and haven't been on it since. I haven't told anyone I've ever been on there, including my girlfriend. But recently I've been catching myself thinking I'd like to go back and talk again with people I've met on there - not to do anything, cheat, or anything behind my girlfriend. I've also been thinking I'd like to re-put some photos I have on there of me, it was nice getting comments from women on them. I know it's wierd but I just needed to talk to someone about this. Chances are I won't do it, as I hate doing anything that I don't share with her, it's like I'm ashamed. I guess I'm more curious about investigating why I've started thinking about this again.