Strange upstairs neighbor

At heart, I'd like to call him insane, crazy or something of that kind, but it's uncertain that my view is correct, so I can call him just strange. Strange? Yes, I may be strange too. But today's unexpected and scary occurrence shocked me mentally.
On the evening, I was going to buy cigarettes to a nearby store. And when I was about to open the door, footsteps of the upstair neighbor were heard. I would avoid to meet him, so I kept myself on the entrance, with watching until he passed through via door scope. As of this time, my thought and behavior might be silly and strange...
The next moment, I was surprised and frightened at what happened to me. The neighbor, muttering something overbearingly, came down to our floor, then, stared at doors on our floor, still muttering something overbearingly. The scene was nothing but creepy. But the real terror was waiting me...
He peeped me! Surprisingly, he peeped me through the door scope on my room! I instantly detached my eye from the door scope, bent and froze myself with bated breath. For some seconds or minutes, he went on peeping and probing something on front of my door. During the fear, my heart beated very fast.
I know that he has strange behavior since first time meeting him. But who would suppose his strangeness appears in this way? Who would suppose anyone would peep through a door scope? Just ridiculous.
I'm afraid I might be injured by him in future... I think it's better way to move out here.