I seriously doubt a real world effect can accidentally cause a car to wheelie! It has to be a miscalculation somewhere, because that wheelie didn't show on an instant replay either. It must be an accidental effect for it not to show up there, or the real time and replay physics are different, which I guess they could be - why program tyre physics for a replay.
I've not tested bouncing diffs/car and then restarted the session but changing nothing else, so I'll do that next time.
Wheels turning against each other makes some sense. Sticking dampers? A deliberate random factor? I guess that's fine, but the FFB needs to respond accordingly to give you a chance of correcting it.