stalker?

hiya. so, i think i might have some sort of stalker. i am not one to be overly paranoid about things, so i really didn't give it too much thought until this morning. you see, in the last couple of weeks i have noticed this guy while parking my car. (i park about 2 blocks away from my building in an open parking lot.) i get there, and he pulls in pretty much the same time i do.....parks a few spaces away. he sits there until i get out of my car, and then as soon as i get out and start walking towards my building - he drives away. this morning, i arrived to work about 20 minutes earlier than i normally do -- and he did it again. i sat in my car a little longer than i usually would... just to see if he would stay or go. he stayed. and when i got out of my car and started walking down the street to my building -- he pulled away. i got his tag number, and tried to get a good peek at him just in case anything ever comes of it. but, don't you think that's strange? or am i just being paranoid?