Priced fairly from your description. I wouldn't expect the old history to have much affect on it at that price, but you can always make a lower offer and then offer more if he balks at it. Have the pre-buy done without mentioning the creases to the third party mechanic. If he identifies them as a potential problem without prompting, then you know. If the mechanic doesn't mention it first, then point it out to him and ask for an opinion. If it's that hard to see, or he sees it and ignores it, then I'm sure it's not an issue.
