Getting progressively more noticeable over a few weeks rather than appearing suddenly usually means the underlying fault is developing rather than a one-off heat spike. Worth getting it looked at before it gets to the point where it affects more than just shift quality.
Went through this exact evaluation last year, tested a small batch in our coldest zone for a couple months before full rollout. Dimensional accuracy held up fine, no picking system issues. The load rating info matters more than people think though, cold makes plastic behave differently under...