My 2015 CX-5 seat is still rocking....its annoying, however, I don't want the dealer to attempt to replace the lower seat unit and possibly mess something else up if the problem is just going to come back again.
I drove a 2016 CX-5 (rental). It had 3000 miles on it and the seat also rocked just like mine. Although annoying, I wonder if they all are prone to the same thing. If the part number is the exact same, there is no reason the new seat tracks wouldn't eventually end up doing the same thing as others have suggested.