I have the same issue with the digital clock. It didnt have anything to do with being cold but I noticed it more in the morning before there was anything good to listen to on the radio, especially driving down the 405 (choppy nightmare)
I havent had the time to completely tear it apart to fix it so i pulled off the radio surround and slid some white closed cell foam in between the head unit and the clock. it took care of the rattle for now.
I also used that foam to line my A pillar trim when I installed my 9500ix, having some closed cell foam around the garage makes alot of interior noises go away : )
13 WRX Hatch - Torqued Performance Stage 1+
Slow is Smooth > Smooth is Fast