If it was a rudder issue, a lateral jerk would have involved a bending moment about the vertical axis (centre of the airplane), as opposed to an adverse bank angle (which would, perhaps, put the wing into the ground). In other words, not the end of the world on its own, although, unpredictable operation of flight control surfaces is a very dangerous emergency that must be rectified.

A significant risk, IMHO, is the development of, especially at higher airspeeds, of a regime where large oscillations in the rudder occur, causing the creation of under-damped oscillations in the rudder/vert stabilizer assembly, and eventually, as in the AA A300-600 that crashed in NYC shortly after 9/11/01, complete rudder and vertical tailfin failure, with results that are often predictably bad.

edit: all single engine propellor-driven airplanes naturally have the same sort of thing going on, because of forces involved in the rotation of the propellor blades. Opposite rudder input is required shortly after takeoff to keep the airplane steady. Not dangerous at all, when such behaviour is predictable, and expected.