I wouldn't worry about the three 13 mm nuts on the top of the assembly. As long as they were tight when installed, they will be fine. They are self-locking and with the weight of the vehicle on the coil/shock, stress should be reduced.

FYI...........I took my ML to a friendly TiresPlus and had them torque all suspension pieces to proper specs. They used an alignment rack which was perfect..gets vehicle up off the ground, but still has weight on the tires.