Brant.....Red bellies aren't uncommon in our area. The birds are stretching their "typical" range; e.g. I have Carolina wrens and Robins wintering here for the past few winters.
I have no doubt you saw a RBWP for there is nothing else in our area that resembles one....next time have your camera ready.
Now just keep your eyes open for a Yellow bellied sapsucker......this is my first winter observing 2 at my feeding stations.