I've been running a Ballistic 17.5 with a swapped stator for the last few months, and I'm having a weird gearing/timing/temperature anomoly.

The motor is under-geared and over-timed compared to the other racers at the track, but it still keeps up with the rest of them just fine. I wrestled with different gearing and timing configurations for a while until settling upon this one. The temperature though, seems to be steadily creeping upwards.

When I originally geared and timed it, it would reach 160 degrees after six minutes pretty regularly. Then it started dropping lower; 140 after 6 minutes, 160 after 20. Now it's on the rise again. Two weeks ago, it was 170 after 10 minutes. Last weekend it was 180 after 10 minutes. Same track layout, same overall conditions.

The motor doesn't seem to have lost any power, it just seems to be slowly getting hotter. Is this a slow failure of a motor due to mild overheating? Or is it just the result of environmental changes causing a confirmation bias?