Was he "hanging out" in front of the store when you pulled up?

He must have caught a glimpse of something. Glad it was handled without having to draw on an unarmed wierdo. Also glad he didn't have a knife, and you kept your cool.
Maybe just an angry, bitter, guy with nothing better to do but try to bully an armed person......That is one day going to get him a Darwin Award.
Amazing how fast a "normal" situation can just change in an instant; your sixth sense worked with this dude, and your whole situational awareness state of mind, really is a good thing to have, that goes for anyone who carries also.
I carry left side IWB, which is my strong side, or back pocket with my P3AT in a Nemesis "wallet" holster, but before opening the car door, I make any adjustments to shirt, and holster, as this side will be the first side facing outward, just a habit similar to when I return to my car.
Glad it turned out the way it did.
Stay Safe.