Sounds like someone who enjoys making trouble. It's very difficult to deal with these types of individuals, because they like trouble, and usually have a complex about, "being right"...... Even if it means trying to make a mountain out of a molehill to do it.
If they didn't, they wouldn't complain about such pettiness. If you're a patient man, I would sit down and make a simple list of points you can make to him about leaving the whole thing at the status quo.
If you know what he drinks, Beer, wine, Scotch, whatever, you can offer it to him. And tell him you would like to discuss the matter on friendly terms.
"Kill him with kindness", so to speak. If that doesn't work, it comes down to just ignoring him, and see just how far he wants to take it. He can most likely make you move it, if it's encroaching on his property.... And that's if he's determined to become a complete prick about the situation.
Unfortunately there are people who just LOVE to do this type of thing. It gives them a feeling a of superiority. Even if it is over something as petty and stupid as this.