Replacing some magnetic vehicle door signs for customer and noticed the vinyl on the old ones was faded and peeling. My records show they're about 4 years old. Used Oracal cast vinyl and was surprised how they deteriorated. Magnets hardly ever removed from pickup. The vinly looks like calendered instead of cast. Never seen any of our material weather sold quickly. Customer says others they've bought in the past have done the same thing. Is this normal, and if so, is the magnet to blame?