You mind if I steal this story for my horror movie script? Yeah, you had legitimate reasons to be afraid.
It's probably nothing, just someone who was in need of driving instructions or something. It's been ages since I was home alone at night. Like 3 years ago I think ? Doesn't matter, I had it once too, I remember I grabbed a knife and kept it with me the whole night till my dad got home. But my 'stalker' didn't came to a windows in the back, that's so rude/stalky ! I wonder why people knock on people's doors in the middle of the night. Drunk teens/people who want to be noticed .. ? Ah well, it was surely not important since I never heard from him/her again.
Don't feel stupid about that Aims. A girl home alone at night with some man banging on the door and then going round back to the window - very scary. A lot of people would have done just about the same thing, SA or not.
I do feel guilty incase someone had an accident outside!