MMM demagged my Novak motor

[SpEEdyBL]

While i was running my MMM/HV 4.5 in on a 4s NeuEnergy 4100 mah pack in my 8ight geared 10/49 today, I noticed the fan came on earlier than normal. The motor was only 160F so I kept on running. Then the oddest thing happend. When I drove down to the end of the street to do a pass, the motor had unusual insane speed going down the straight. I had to see that again so i drove back down to the end of the street again, a little further this time. However, the motor started to cogg pretty badly. First I thought it was radio interference, but as the car got closer it still cogged and had barely any power - as if an extremely weak battery were plugged in. I picked up the car, and the motor still struggled to start up even with the wheels in the air. I immediately turned everything off and the motor was 200F and probably hotter inside! It also had a pretty bad burning smell and the shaft would turn with almost no resistance. I figured rotor had demagged, but I am quite uncertain as to how. The magnet did not come apart from the shaft and the temps were no were near the 180 celcius (356F) mark that novak rates their rotors.

I am posting this here just find out if other people have had problems with the MMM demagging their motors, and if so, which motors they were. I know the novak motors weren't designed to run sensorless but they seem to run pretty well on the MMM otherwise.