I've had similar experiences. Today in trials, I jumped toward the outside heavy ammo and was killed by a "misadventure" upon hitting the ground. I hadn't taken any damage, nor were any enemies in sight. I just died, and my team lost the round because of it. Edit: I also had an infinite rumble match, but that was a few months ago. Everyone had at least 20,000 points, and no end was in sight. I didn't know it was happening to other people regularly.