Yes for a surge alone the engine will rock and vibrate simply because the surge is localized and rotates backwards to the spinning rotor at about 1/4 rotor speed while at the same time producing pressure pulses at a rate of about 7 per second.. Since the mounts are single point in the top front, this rotating pressure wave causes the engine and pylon to shake and in turn the wing and passengers as well. It's all very short lived until the pilot retards the throttle and reduces the pressures in the engine.
Thanks for the explanation. It makes sense now. My initial worry was that the shaking of the aircraft might indicate some kind of imbalance in the engine (such as rotor damage).