I would tend to agree. That it's most likely installation damage and that it's not worth losing a friend over. If it were me I'd be searching for touch up paint and just do the best fix you can. Chances are you are the only person that will ever notice that it has been touched up. I remember selling my SVT Focus several years ago and the car was almost perfect but had one little dent. The buyer searched the car over and finally put his hands up in the air. So I showed him where it was. He couldn't have cared less.