Thanks for the support, everyone. I think I would have handled the situation entirely differently had A) I been in a better mood had I found the cache and showed him, or C) if the owner had said in a friendly voice "hey buddy, everything OK over there?"..however, his body language was defensive to begin with.
Here is a little more background about the layout around the location of the cache (that I didn't find, BTW).
A main road is fronted by numerous shopping centers. with the parking lots all connected. Think of a large grocery store parking lot..this man's land, which has a stand alone building about the size of an 8 screen movie theater on it, is adjacent to the grocery store parking lot. I drove through the grocery store parking lot and continued through the parking lot on his property to get closer to the cache. As a matter of fact, I even saw the owner arrive in the parking lot that morning (a good 250 feet away from the cache) because I passed him in his car as I headed toward the cache. I have no doubt the guy was the landowner because I used to live about 1/2 mile from this location and patronized the business that was located there years ago before it closed.
As I drove through the vacant part of the lot, I saw the only logical area where the cache could be --somewhere on a probably 20' wide strip of land separating his parking lot from the parking lot on the next strip mall (this strip of land also meant the end of driving through parking lots as a way to get from strip mall to strip mall). I don't know if he owns the grassy area where I was searching or not. I suppose I will e-mail the cache owner to let him know of the guy.
I'm usually aware of all my surroundings--I had my eye on someone unlocking one of the offices at the next strip mall while this guy was walking toward me. Had I spotted him walking toward me, rather than worried about being muggled from the nearby business, I would have been long gone before he got there.
If the guy has noticed activity over towards that corner of his property (whether or not he owns the land where the cache is located), then IMO he could have approached me in a more friendly inquisitive manner. It is indeed a relatively new cache...one that I won't bother to find.