Problem(s) Encountered:

About a dozen times tonight, rather intermittently but perhaps more often in the north, the telescope would jump eastward and kick the guide star just out of the box, maybe 10-15 arcsec.  
Pushing the east guide button for a few seconds brought it back in, but it meant I had to pay more attention than usual to the tracking!

Solution:

Sounds like a subtle artifact from the RA drive train.  Jacked up the telescope and reseated the roller.  Checked the 4 mounting bolts for the preload plate and replaced them with new ones (old ones felt mildly stressed).  Checked spring plate tension.  Felt good.  Let the telescope track for an hour.  Went from RA of 11:21:00 to 11:21:03.  Perfectly acceptable.  Hopefully the problem disappears.