Fluctuating charge

Is there any legitimate reason that the alternator/regulator may be computer controlled on an 07 allowing the voltage output to drop to 12 volts if the battery is fully charged?
I know on any other vehicles charging should remain consistent at 14 volts but my Av will start at 14 volts then after a little driving it will fall to about 12.8, sometimes it will go back to 14 with continued driving and go back down to 12. It will continue this cycle over and over. Turn the lights on and it only climbs to 13.2
Is this a normal computer controlled action or is the alternator failing? I suspect failing but wanted to ask before I replace it.

Thanks guys

I believe there was some info on this in an older thread stating that fluctuation like that was normal on the newer computer controlled vehicles. Not sure if I remember reading correctly but I think it had something to do with gas economy and running stuff on the AV.

Totally normal:
check out this thread
http://www.chevyavalanchefanclub.com/cafcna/index.php/topic,150266.0.html

awesome..... Thanks for the info