I've seen this a couple of time with both probes and craft, I select a heading on the navbal such as prograde, the ship slews to the correct heading and once it gets there it starts vibrating. It seems like it is over correcting, correcting, over correcting, correcting and repeat but a very slight correction. If you warp while this is happening you soon find your battery dead or monoprop gone or both. If I turn on heading hold, this doesn't happen, just the other settings, pro/retrograde, normal/anti-normal, anti/radial. I launched two identical ships carrying solar panel struts for my station, the first one did not show this problem, the second did. I tried returning to spaceport, and re-starting the game. I've tried toggling torque, which corrects it but it's hard to hold a heading, I've turned off gimbaling of the engines which sometimes does the trick. So, after the wall of words, is it normal to experience this phenomena?