I've picked up some almost golf ball size rocks on the deer foot in the summer and have been pretty lucky. I've been running my window for 4 years and this is the first season I should have actually changed it, 99 percent of the rocks just chip a small piece of glass, but no cracks until this year, I think it was a dealer install, but I'm not sure what brand they used,
Maybe the combination of cold? My friend cracked his window one time warming up his car in -40, no rocks needed