flickering headlights

Has anyone noticed that the headlights seem to flicker on their NBS Silverados?  I have a '07 NBS Crew and have noticed a brief flicker or dimming of the headlights while driving at night.
 
It only occurs for a fraction of a second.
 
I haven't been able to determine a pattern, like when the brakes are applied or anything else electrical comes on (because it doesn't happen all the time), but I think that it is when it generally happens.  I havent' noticed that the dash lights do this.
 
Haven't notice any changes in the gauges.
 
Am I just seeing things? 

I know what you mean, I have the same problem. Its only the headlights, and it seems like its only when the truck is idling down, like coming to a stop or at idle. They will dim for a brief moment then get bright again. I dont know what causes it. The voltage seems fine, IDK.

I know this is a bit late if you haven't gotten an answer yet... 

A friend of mine who is ASE certified said that is related to the alternator.  Someone else had the same issue you mentioned and that's what he mentioned to me.  I vaguely remember that same issue I had when I owned a FZR 600 and after replacing the alternator it went away, but that is when I used to work on bikes many years ago and completely forgotten about that...

Thanks!  I'm just waiting to see if anything gets worse.  Warrenty should take care of anything for now.

Check the alternator.  If it is good, probably a bad ground.