The ceiling in my trailer consists of panels separated by strips every 4 feet. Over the years the panels have wrinkled where they slip under those strips. I firmly believe this is at least partially related to warming/cooling cycles especially when the roof is weighed down with snow.
The freeze/thaw cycles always scared me too. It's very difficult to get all the snow off the roof, but when it's deep, I try to climb up there and get the bulk off.
Last fall I decided I wanted to get some more years out of my 15 year old trailer and had the roof shrink wrapped like they do with boats. No worries this year. I'm going to try to get a few years out that plastic.