Just curious I guess. When I get a new Castle ESC I always load it to the newest firmware because many of the updates have bug fixes i.e. it is a little bit broke, it does need to be fixed. Don't really care about getting extra features or functionality for this air ESC. When I did the Phoenix I noticed the behavior so I asked about it. For now I'm sticking with the latest 3.xx
With our aircraft ESCS, if they start behaving badly go to off throttle. It will then start to beep and flash 1 to 6 times over and over until you throttle back up or unplug the ESC. These are error codes. Check the manual that comes with or the one online to see what these are.