OK heres the deal:
2002 2500 with 182,000 miles, no mods.
When I start cold I get the battery light in the message center for a good 1-2 minutes and my voltage is down around 9.5 volts. After the 1-2 minutes the batt. light goes off and my voltage gague jumps to 16(ish) volts.

I did a search and see a lot of stuff about the intake heater running during this time, but my truck has never done this before. Am I just being a little bit of a hypochondriac? Or do could I have a problem?

put a volt meter on it after a cold start to confirm. the factory gauge isn't all that accurate. also, make sure all the connections are clean and tight. this usually goes without saying, but a lot of people skip this step and rush to condemn a part. also, how old are your batteries? maybe load test them to make sure all is well before chinging up for a new alternator?

Update and correction:
The low voltage on the dash is showing about 12 (not 9.5). Now it does not want to come back up. Just ran to the store and back (about 10 miles/10 minutes) and it sat at 12 volts the whole time.

Where do I put the volt meter (sorry I just dont know)?

OEM batteries? If so, they're probably tired and need replacing. Replace them both.

Whoops, forgot to post that. Batteries are Diehards, about 6 months old.

mine is doing the same thing, but it died and won"t start now.. going to get a new primary battery, but need to now where to test the altenator at also.. sorry for jumping on your post, thanks for your help..

Discovered this morning if I floor it, the voltage gage on my dash will come up to 16(ish) volts and it will stay there.

Got it over to Carquest, they put a tester on it----Charging system error.

replaced alternator, life is better now.