My driver's side seat has a couple of weird spots on it. They're small and completely unnoticable unless you're really looking closely at the seat, but they're small circular areas that are slightly lighter than the rest of the seat. I tried 3M leather cleaner and conditioner on it but it doesn't seem to do anything. When I run my finger over the area it doesn't feel like there's anything on the leather, it's as if there is just a lighter area of leather in these small spots. What could cause this kind of thing?