Does old paint become plastic?

[Jason Hallway]

There is a strip that goes along the top of all four walls beside the ceiling. At first I thought it was some plastic film that had been stuck on because when I peel it back, it comes of in a strip of a 5x5 centimeters. The top layer is white, bottom layer is yellow. So... when paint gets old does it end up behaving in this way?

Thanks for your time

[Mr Fuxit]

This is because the paint was applied to a surface that was not properly prepared by sanding (to give a "key") and washing (to remove grease).