As has been said it jerks due to friction of the seals on the fescalised (sp) area of the oleo. The 777 also does it but not as bad as the 330. The 330 will jerk more readily as the oleo is at an angle, not verticle. If the wheels are not chocked correcly to allow the aircraft to creep as the weight increases then this jerking action can be quite severe. There is a note in the AMM about it but I ain't looking for it now it's too late.
Hope this helps.
