jfvcms,
Taking the pressure down a little and then back to the recommended PSI was the first thing I did when the light started going off, but thanks.
Took it to dealer last night. Apparently the wheels have some kind of embedded/coded serial number (this may be the same thing as the valve stem sensors, I don't know). But anyway, the wheels/tires on my '04 were switched at some point (mine has Michelins rather than the Dunlops that seem to be on most). When they were switched, the new codes from the wheels weren't programmed into the ECU, so the computer was picking up the signals from the old wheels. Dealer broke down all four tires/wheels, got the codes and programmed them in, and all is good to go.
Got an SR5 because I DIDN'T want a bunch of electronic crap on it that could go wrong, but I guess that's the tech world we live in. Other than this, absolutely loving my 4Runner.