That's odd. I had a creepy neighbour experience when I lived at my first apartment. We had balconies but these were open - so basically you could see anyone else who was on their balcony too. One guy 2 apartments down from me seemed to listen for me to open my door and he could come out too and just *watch* me. I mean, sometimes he'd try to pretend he was doing something else, but when I'd continuously go to my balcony to have a cigarette, and he would come out not 5 seconds after I did, it got to be rather creepy.
Even if I wasn't on my balcony he'd still watch me. Once I was leaving the building and saw him coming from the parking garage. I started walking faster, I was maybe 40 feet from the building when I hear keys jingling LOUDLY and when I turn around he's standing by the building, jingling keys and looking at me. WTF.
There were a couple of other incidents but after that one I told the landlord (I wasn't sure what else to do), and she talked to him and he didn't do it again after that. He was an older man, maybe in his 50's and I was 19 and lived alone - so yeah, I was kind of freaked out.