It can happen John. The cream Aero S5 demonstrator which did the dealer circuit last year was badly discoloured on the side of the backrest. It seems worse with lighter colours.
It can be repaired with dye and 're-laquered' as a diy solution.
I favour 'Furniture Clinic' but some use 'Gliptone'. Both available on line. You may have to supply a small patch of leather from under the seat to get the right colour match.
