I've had my '05 645cic since new but recently started seeing a blue staining on the rear deck lid at the locations where the rubber gaskets rest.

Normally I wash the car myself with Mr. Clean auto wash and never had a problem. Lately because of construction around my house I have been bringig it to a local car wash who has always washed my other cars. They insist that the only blue liquid that is in their facility is the spray wax, which I've never had applied.

Has anyone else had this problem and if so, any thoughts on how I can remove?