You could get the shop to put some of that clear plastic frame protector on it. I know they make it for mountain bikes so hopefully its available for road bikes. You could tell them that your bike doesn't have any marks on it and you want to keep it that way. That may then lead to an inspection while you're there to be sure there are no marks on it. I don't think this would be offensive to anyone and you would end up with a bike that should sty flawless for longer. It might be pricey though.