I can't see this happening with chains jumping cogs or gears jumping out of mesh, you would have serious issues and it would happen more often. I am thinking its transfer case wind up and its releasing as a reaction thru the wheels/suspension. I had a pinion bearing fail on a landcruiser and it went bang in an instant, however didn't manifest into a total failure until 200klm down the road. I would also revisit the pinion bearings for movement, however would think the gear set would be well and truelly gone by then, as mine was.