AI and static vessels don't truly interact with the environment unless the "always awake" setting is switched on. This means their location is an approximation. When the player vessel gets close, the position is calculated accurately. This may some way from the approximation, so the ship will lurch into the new poistion.
I've noticed the same thing with static ships when I am producing new missions. The larger vessels are the worst affected (or perhaps it is just more noticable).
As the player ship comes within the "come-awake" radius of the static ship, the static vessel will go from zero to top speed almost instantly and rush forwards. I found that with Lattitude or Vermaas, the effect was most disturbing.
You can see a similar effect with AI ships as the player vessel gets close. They often rise into the air by several feet and then fall back.
