Just got a P4 and flew it around a few times before hitting a tree. Other than a few busted props, fortunately the damage was minimal. But now it's telling me I need to calibrate my compass. I do that, and it says it's successful, and it flies. But the warnings won't go away and my P4 seems to drift more than it used to (which is probably why it's telling me to calibrate). Is it normal to me able to fly it when the compass is apparantly not calibrated?