Experienced the bug on a fairly frequent basis still running beta 10 (at least 2-3 times/week driving to/from work around 45 minutes per day); The bug was originally more prevelent on the volume up, but I'm noticing it more now on the volume down (coincidence?) not that big a deal for me though - I can usually spot it happening and stop it before it completely runs away.
-mark

...proud to have one of the first Mark I units