I took it into a dealership today, primarily because my screen experienced the common defect in the corners - that will be replaced via warranty. However I also mentioned the rebooting issue in the cold weather, and they informed me it's a known issue and the cause is the nav SD Card. The solution is to replace the SD card, but the lady wasn't sure if that would be covered. She did suggest that one way to "solve" this is to remove the SD card, warm it up in your hands and then re-insert it. Or bring it into the house. I don't really consider those solutions.
So, I guess we'll wait and see what they say when I take it in next week.