Yea, just the same, car (98 UK GX) was serviced 2 days ago by Toyota Main dealer. Today light comes on with hand brake. Does not go off! Look closely it goes slightly dimmer when releasing HB.
Manual states if it stays on, then check fluid. Reservoir is full. Uh! I had my timing belt done at service, so they may have damages the sensor (on UK models the Reservoir is near that part of engine. Is the reservoir meant to be wired up from the top, If so mine is not.
I'm taking it back to the dealer since the service was £350 Stirling, and the Hand brake is not as efficient as prior to service.
Will let you know outcome, it may help!