Moving blankets safe for my paint?

I recently moved my '69 Dart project indoors. The space is tight and I planned to cover the car to help prevent scratches, etc.. I purchased some of those cheap moving blankets from HF. They are made with polypropylene front and back with cotton in between. Should I be concerned about any possible reaction between the Poly and paint? Plastic, petroleum based product, right? Any thoughts? Comes down to it, I can throw a cotton sheet over first.
Thanks