I don't think it's the weather cause it used to happen in my old car all the time, but not in my new car. In fact I can believe it's the seat material cause the old car had velvet like seats which gave me the creeps but now I have leather and no problems. I Wonder how much it would be to get aftermarket leather in the tC.... the seat material is really weird it changes color depending on color reflection from the outside, on some cars it looks blueish, on others purple or red while I'm told it's really just grey/black