It's stalking. Even you call it that.
Look, just imagine if she became aware that you were following her? And you merely turning up to where she is going to be amounts to that, ESPECIALLY if you are attempting to keep your identity a secret. If that was me (and I'm no faint heart) I would be majorly freaked out. I wouldn't feel safe going out again for fear I was being followed. SHE doesn't know that you are harmless. It's not flattering, it's creepy and and it's scary.