You're already feeling guilty - therefore it seems more than casually going to check her out. The problem with guilt is that later on when you know her better you might feel the need to confess, then it will lead to an awkward horrible conversation about boundaries and compulsiveness, which could all be avoided by using discretion. I don't see the harm in bringing up your feelings about the whole thing when you meet. But if you're feeling like it's stalking it probably is.