I just want to join the choir. My FP2 also reboots a lot during Pokemon Go. Both while it's cold and warm. I have not found a fix to this.
Also I've experienced unwanted reboots whole using facebook, and just plain old chrome. But they are not as frequent as they are when I try to play Pokemon Go.
Normally I wouldn't reply like this, but it looks like a lot of users have this problem, and I just wanted to add to this.