It was intermittent, and I really didn't have time to deal with it. OTOH, I knew its third birthday (and thus the expiration of my AppleCare) were coming up this month. Then Tuesday morning it did it again, lighting up its screen, making CD-eject noises, and running its fan on the breakfast table, ten minutes after I'd closed it. And when I went to log in to try to put it to sleep again, it locked up.
So I took it (in it's locked-up state, so they could do the reboot themselves and look for clues) to the shop (the shop being The Computer Loft in Allston, which as best I can tell is the last of what was always a rare breed: independent computer dealers with clue.) This afternoon they called me to say it was ready: they had replaced the main logic board, where a USB chip had gone wonky, under AppleCare. They had also noticed a small crack in its case (which I had noticed long ago and forgotten. This turns out to be a known defect in early MacBooks, so they also replaced that under AppleCare. On MacBooks, the keyboard and trackpad are integral to the top case. Which means that the part of the computer I actually touch, and consequently the part that shows physical wear, is now brand new. As is the main logic board.
So if you squint a little, I essentially I got a new MacBook today. For free.
I'm good with that.