I used to drive past my T's house in the beginning. Actually I did it during the first summer when she was gone for two months and I was missing her horribly.
I never felt guilty about this and I never told my T.
I don't believe you want to stalk yout therapist or hurt her, you're just doing it to feel closer to her presumably.
Like rainbow said, I think you should tell her as you can't seem to stop and while it's totally understandable, it's also not healthy. I'm sure your therapist will understand the urge you had.