I also noticed the audio dropouts on KSDK-HD when watching previously recorded Heroes and My Name is Earl episodes this week. So far, that's the only channel I've had the problem on.
I have noticed the drop outs on the St Louis HD Locals, but it only occurs with programs that are on the DVR. The live brodcast seem ok. I believe this is a problem with DISH Software. The resent update has mede it better but still problems