You're probably right. In my limited experience first the PEM would give temp warnings and then the motor. I suppose in lower ambient, the motor might start yelling first.
That is what happens in Seattle with my Roadster 2.0.
The motor is what gives the first temp warning. I have never received a PEM temperature warning. It takes a lot of spirited driving for me to even get a motor temp warning.
It is rarely ever an issue for me even when I am having fun driving in the hills for a long time. Lots of curves with accelerations, still no temp warnings.