So after soliciting a whole lot of advice running to the contrary, this may go the way of let bygones be bygones as if it is a 'favor' to the neighbor? What favor? If the neighbor was in town when the work was done, he is complicit. If the work was completed in his absence and he indeed confirmed the boundary, minimum setbacks and location with the contractor prior, it is clearly contractor error and no skin off his shin to have it corrected. I should think the neighbor, in HIS efforts to maintain good relations, would be going out of his way to have it corrected ASAP. I know I would. I also know if MY neighbor didn't attempt to make it right... well, let's just say, I would be suspicious he knew what was happening all along and just keeping his fingers crossed I would let it slide. Who knows what possible future problems that buys. I do know nobody appreciates being taken advantage of and you can bet I'd be unwilling to do him any 'favors' now or in the future. Assuming the neighbor's total ignorance, I can appreciate not wanting to rock the boat but the only party making out like a favor bandit here is the contractor.