I believe I've identified that mystery bird I saw for a second or two on the platform feeder on Saturday. He appeared again on the suet feeder yesterday morning as Kat and I were digging a big hole to find our well. (long story--suffice it to say, there's still a big hole in the backyard)
As I said, he appeared again at the suet feeder, and I got to look at him for a little longer, and I noted a distinct red patch on the back of his neck (his nape). Turns out I'd seen a female red-bellied woodpecker. I still didn't get a photo, but I'm pretty confident on the ID. Definitely a female, as the red patch was only on the nape, not on the head as well.
Thanks to whatbird.com -- and the bird herself for making a second appearance so I could spot that red patch.
One note needs to be set down, however: Look at my original description and see all the crazy characteristics I attributed to the bird that could not possibly have been there--"crested head"???? Oh dear. Hallucination? Bad memory? Bad eyesight? You decide. Needless to say, this beginning birder might need to study up a little more on key identifying characteristics to look for--and carry a camera on her person at all times.