I'd be surprised at an uncommanded movement. I think the issue here is putting serious stick force to counteract the lack of hydraulics and then with that force still applied flicking the hyds back on... then for the unwary you get a sudden "geared" and substantial deflection..
never happened to me of course but "a friend of mine" might have accidentily switched off the hyds with his map whilst leaning it on the cyclic and then leant down to pull the breaker with head down on the floor and significant forward pressure on the stick...
If you know what to expect o wouldn't expect it to be a significant issue and I certainly haven't seen a p.o.h or safety notice restriction...