Tony,
that's awesome. I'm no expert on controllers, but even at idle speed your controller is working to maintain the low rpm and may be getting hot. All that voltage needs a place to go. Rob H. might know better. It may be best to let the prop windmill at 0% throttle if the controller is getting too hot. Of course, adequate airflow will prevent this. Controllers tend to run hotter at partial settings rather than full throttle. If you have an IR temp gun, be sure to check the motor+esc+ batteries. I don't have anything remotely as big or costly, but those who do check the temps of the motor and controller. Demagging a motor or smoking the controller will ruin your week.

Just my .02

Terry