Just wanted to chime in here. I think it may indeed be something to do with the cold, but perhaps not *just* the cold. Being from the Western NY region myself, we tend to have a good amount of humidity from Lake Erie. I can't help but wonder if the humidity is the 1st part of the equation and then the cold is the 2nd part. I say this as a Laredo owner who just started hearing a whine / squeal after about a year and a half.
I did look on youtube and see one guy messing with his Traeger, and he had success unplugging the various components. He tried isolating one fan, then the next, and it was the 2nd one. Pulled the fan off, popped the back plate off the fan, chucked some grease or oil in it and put it back on. He came back and mentioned a while later that he'd done quite a lot of cooks since then with no issues. Whether any of that is actually relevant in our situations, I have no clue.