Alternator problems in a 2002 Tahoe?

Hi everyone! I've got a 2002 Tahoe LT with 39k miles on it. (figures, the problem starts just as the warranty ends)

A month or two ago we noticed that we thought the interior lights may have been flickering a bit when on and the front headlamps seemed to flicker once, but I assumed that it was because of temperatures around 0 F.

Today I was out running errands and after starting up the car as normal, the battery light on the message center didn't go off. I drove a few miles, had to get gas, and when i turned the car back on, the light (as normal) turned off after the car started up.

I'm hoping the lights were a fluke, as I am still having a hard time believing a 2002 car with under 50k miles and JUST out of warranty needs a new alternator. Could this be something else or are alternator issues with such a new car "normal"?

Just out of curiosity, what was your voltmeter reading throughout all of this?

It was steady at about 15 the whole time, which is where it's been since it was brand new.

Just wondering, cuz mine only reads about 13 all the time, but I've never seen my indicator stay on after initial startup... I'm half thinking the output may be a little lower than it should be, but so far I've been too lazy to verify it with my own DVM. Maybe this weekend... At any rate, mine is still (luckily) under warranty.