Did you just check the vehicle for codes in the computer?
I used the hand held computer and it said all passed
Correct, that is what caused this condition. For future reference, leave the 4Runner running when checking codes and this won't happen. Yoy should see a code C1203 stored for Zero Point Calibration Undone. Here is the TSB that will help restore the calibration...
Please reply back if you still have questions or need help.
If the light comes on and stays on, then fill all 5 tires to 36 psi and the light should go off by itself.
If the light comes on, flashes and then stays on, then there is a problem with one of the sensors and it will need to be replaced and coded to the computer.