Next time when you start your autoguiding, note down the x-y star location at the bottom part of the autoguide window.
After an hour or so, go look at that set of numbers again -- did it move by more than the number of pixels that you have selected in Dither Settings?
If it moved, turn off dithering and watch those numbers again.
Dithering is supposed to have zero mean (i.e., don't move in the long term). But I seen a lot of images on the ASIAIR Facebook page when a hot pixel keeps random walking further and further away from the start. ASIAIR could be dithering from the most recent location (bug), instead of dithering from a fixed location (correct way).
It is possible for random walks to move very far away from the starting location (this causes the "Gambler's Ruin" problem in Probability Theory), but it should not be common with guiding dithering. This is probably another bug in ASIAIR.
Chen