I seem to be only having the issue with the passenger seat but that doesn't mean the driver's side wouldn't be a problem if I could drive without sitting in it. If someone is sitting in the passenger seat in cold temps that seat doesn't make the noise. So having weight on the seat or pushing the seat stops the noise. This kind of makes sense as this would slightly move the side plastic part away from whatever it is rubbing against.

I have tried to take the plastic cover off the seats but found it has a formed in clip on one area that doesn't come off. After some reading in other forum some have had to break the clip to get it off. They say it doesn't effect putting the cover back on. It seems idiotic though that Toyota would design it this way, because if they have to get in there I assume then they would also have to break it and then replace it after doing so, costing the customer more money.