S500 Lamp burnout indicator lights when nothing wrong

[Ken Griffith]

My lamp burnout indicator keeps lighting up(only when I hit the brake pedal) periodically. It happens when I have the lights turned on or not, indicating a brake light issue. I can stop the car and put it in park, have someone put on the brake and all the lights are OK.
When I turn on the lights all those are OK.

When I turn the car off and back on, the indicator turns off until sometime in the future when it misteriously turns back on.

Any place to start is much appreciated.