You did absolutely nothing wrong. You drove past her house. Nothing else happened.
Of course you want to see where she lives, it's natural curiosity.
I don't see the point of telling her, unless you really want to, because she may feel creeped out. She shouldn't in my opinion but that's a possibility.

My therapist practices from home so I see her house all the time, there's no mystery there but once or twice, when I was missing her, I drove past her house. Just to know that she was there (the light was on) was sort of a relief, I was looking for a connection. I didn't feel guilty and never told her.

If my therapist didn't practice from home, you'd bet I would be looking for a way to see her house! I don't know, to me, it's just curiosity mixed with a deep yearning of connection. Nothing to worry about.