Neighbor Wars?

We live next door to a guy who lives all by himself in a big old house. People rarely come over. He rarely leaves. I think he is retired. We have lived here for almost two years, we have talked to this man maybe four or five times, and only one of those times did not involve him complaining to us about something.

Yesterday the propane guy came out to check out the tank (FYI, small leak, now fixed, we have the stove back) and because the access to the tank is easier from our neighbor's driveway, he pulled up there in his truck.
In all honesty, it does suck that it is set up that way and I wish the tank was more easily accessible from our own driveway, but we didn't set it up that way and there's not much we can do about it.
And in fairness, the driveway at this guy's house exits onto our road, though his address is on the cross street, it passes about 10 feet by our house and is RIGHT ON the property line. So everytime he does leave the house, we know about it. We can see right into his truck from our dining room. That sucks much worse than a propane truck temporarily occupying your driveway (100s of feet from your house) maybe five times a year, maybe.

Anyway, so this guy comes running out of his house in his boxer shorts all huffy and puffy about the truck being in his driveway.
"I need to talk to YOU. The driver."
He snaps his fingers and points in front of him, like you would when you called a dog.

The driver was like, whoa dude, I'll just move the truck.
Bob says to the neighbor, "You told the last guy that came out here that it was OK for them to use your driveway"
The neighbor says "Well, this is not OK"
Huh?

Anyway, he stomps off all huffy again mumbling something about the tank being right on the property line, it's illegal and we should have to move it, blah blah blah.
Whatever dude.

Meanwhile, Bob decides he needs to get a surveyor come out and mark the property line and then put up an ugly fence.

Yikes.
I think I'm in for a long summer.