Originally posted by H-A Stud
It could be oxidation. Like fuji said, the gel needs to be stripped and re-coated. I'd get it clear coated vs re-gel coating it 
The gel coat is part of the carbon fiber in a way now, stripping it would proly destroy it, and sanding it would make it a lot worse, i think, im not really sure he has a lot of options at this point.