If its just a superficial wound to the gel coat, the current appearance is not suprising. No matter how good the gel coat match, when it oxidizes it will not match the surrounding hull perfectly. Our boat has a repair. Looks great for about 4 months then the gel coat oxidizes a bit and its obvious there is a repair. Rub it out with light compound and wax and it is undectable until it oxidizes again. If it were below the water line, or where a bulkhead attaches I would be very concerned, if not, just have the surveyor check it over well and get a satisfactory explanation from seller.
michael
michael