it's okay to be a little paranoid. there are a lot of bad guys in this world and you have to be on the lookout for them. I've been a paranoid bastard for about 15 years now, always watching my mirrors, others peoples' hands at gas stations, etc. family always tells me to relax.
A few years back I'm pulling into a pizza joint to run in, and a car with two youths pulls up behind me, blocking me in, and 2 men start to get out in my direction, hands on something below window level. I had my own glock of course, pointed down, and I mouthed the words 'no' to them as they started to open their doors.
whatever they were doing there, they mumbled to each other and got back in and calmly drove away. of course i believe they were about to take my money or the car. no other reason to block me in, approach, freeze, then drive away like they got caught with hand in cookie jar.
it's good to keep an eye on others. The world would be a better place if everyone did this. If 15 years of being paranoid means I wasn't robbed once, it was worth it.