I doubt if it's a Recall although anything is possible - at least there's no word on this side of he pond. The nut for that bolt is the self-locking type so if it was tightened correctly at the factory, it's highly unlikely that it would have unthreaded itself.
It's hard to imagine the lower shock mount "shearing" that bolt. Are you sure it wasn't just pushed way far to the right with the nut off? It's an allen bolt with the head on the right side of the shock mount and nut on the left. And the head of the bolt fits tightly into a recess in the shock mount. Visual access is only possible from the left side, looking around/under the preload adjuster. From the rght side, there is too much stuff in the way.