@zebratron2084 If it helps, based on rabbit care, the first time you see them doing something that instinctively alarms you and makes you want to rush them to the vet because they must be on the brink of death, it means "they're very happy and feel secure and love you very much".
Good luck and have the part of you that forms plans work out the measurable phenomena that justify calling the vet.
@zebratron2084 Not sure if kittens do this, but there's a reason rabbit owners speak of the Dead Bunny Flop.