I would expect the gun to come back in the same condition as I brought it to him, other then the requested changes. I think this is rediculous, everyone makes mistakes but just to give it back to you without mentioning it would piss me off the most.
If the guy told me he made a mistake and screwed up a barrell, well then we could talk about it but to just show you no respect, like your too dumb to even notice the scratches would upset me more then the scratches themselves.

Who cares if what he does doesnt effect the operation of the gun or not its wasnt scratched when you brought it to him.

If you took you car to Jiffy Lube(or wherever) and they scratched the paint while changing the oil somehow the care would still drive fine but wouldnt you want it re-painted. I know I would.