sybcronizing upper channels with voice.

Noticed a anomoly and this is NOT weather related.  Exaple:  Clear day, early AM watching C-SPAN or C-SPAN2 and noticed voices are OUT OF SYNC wit hthe lips.  Changed HDMI cable just to see if this fixes the problem.  Same thing.  Re-booted the HD receiver.  Same thing.  Changed to a lower channel (4 or 5 don't remember). went back up to C-SPAN and noticed NOW its in SD and all voices match.  What gives?  Ar the satelites not matching to broadcast?  Or are they picking up something not there?