Again, I think it has to do with the cold weather. I believe the last time you drove the car was in warm weather last year.
If you had gotten your lazy ass to the New Year's Cruise, you would have discovered it earlier.
BTW, my '15 Mustang is almost impossible to accelerate without wheel spin in the cold weather. Pirelli P Zero with a 220 UTQG. And they don't make any tire squealing sound.
Yeah I think the subtle drift you are experience could definitely be caused by cold pavement/tires. If it continues when we arm up a bit you may want to have alignment checked. It looks like Elder's ass is drifting a little left.