I took my Quanum Nova out today for a maiden flight. I have been into RC planes for years. This is my first quad. So, I'm a newbie again! In manual mode everything is fine. It works beautifully. When I use stable mode everything except throttle response works as expected. When I land and push the throttle to off the props increase speed and keep spinning for about 6 seconds. This flips the quad on its back and the props dig into the ground. If I switch to manual before I land everything is OK. Is this normal operation?