Girls, I am a guy and a girl I hang with casually said I was one of the girls.?

Girls, is this a good thing or a bad thing? I have totally sensed a change in my behavior since I started hanging with the girls. If I can not make an outing, I thank them for the invite then apologize for not being able to make it. I find myself complementing a girl on the color of her top or telling her she has cute shoes. I even add OMG and ;-) to e-mails. I just feel like the girls don't see me a a guy but as one of the girls. Am I just one of the girls? I mean, I was with the girls tonight and watched Grease, not the super bowl.