I have. I think the worst thing that can happen is it manages to get hot enough to loosen the adhesive and it falls off. I don't know that for sure but that is what I think. I think the sun in Fl makes it a lot hotter than the mirror would get in the winter. I did ask a dealer and they said "not that they know of". Not sure that helps though.
i checked this out by searching the web, found the answer on the Dodge GCaravan site--consensus, not to worry, no problems. I have had them on my OBW since about the first week, and although it hasn't been cold enough to really use the rear window defrost (linked to mirrors) for more than a few minutes, I had no problems. Hope this helps.