Noticed a small crack on the top shell near one of the motors (see picture). This is strange as this Phantom has never been crashed, tipped over a couple of times on landing yes, but never crashed. Is this a dangerous situation where it could cause the air-frame to fail in mid flight if the crack progresses more, or is it something I can just put some glue on it and not worry about? Does the motor attach to the bottom frame, the top or both? I am deciding whether to ground this copter while I have a chance to buy and replace the shell.