I have exactly the same issue on my game, and I've seen it on two others. I came to the same conclusion you did-that the NC hit switch is triggering as the mech drops on one of them. I've tried adjusting it, and haven't had any success, so I've just ended up living with it-it's not a game breaking issue anyway. I always figured that it'd be something that needed to be fixed in code with a de-bounce timer on reading the NC hit switch after the latch was released.