I have a very weird problem and not sure if it’s caused by the very cold weather today but here goes. When driving home from work today I noticed my drivers side door mirror glass was moving up and down only the glass not the whole mirror as if it was being done by the adjuster, so I pulled over and checked to see if it was loose and it wasn’t. I continued driving and realised it only happened when I accelerated as if through interference. I’ve noticed it doesn’t do it when I’m stationary and Rev or in reverse it’s only when I’m driving along and seems to move more the faster I go

Has anyone had this or knows what the cause could be? I was thinking the weather as it was -6 on the way home.
Thankyou in advance, Craig