Flame rollout sensor keeps tripping

Question

Our furnace stopped working so we called a repair person. He reset the flame rollout sensor and it worked - through 1 cycle then shut off at the end of the cycle. We replaced the flame rollout sensor. The furnace will work if we go under the house to reset it each time. While we're watching the unit, the sensor trips near the end of the cycle or is the sensor tripping and ending the cycle?