oldhornet,
That is the key! I think so it is a bad gyro, usually in roll. Look at the channel indicator to see if the needle jumps, and look for that cyclic throb (oh, throb! throb!) which is what we call sas nibble, when the sas servo moves the stick instead of the main servo.
The AP check grabs the gyro while it is spinning up, and that makes the nibble far more noticeable.
Good luck.
BTW, just go to the left where the username is on any post by that guy, left click and pull down "send a private message to....." to get to the PM page. Look to the top right of any page where it says Privat Message to see if you have one waiting for you.