My brakes work normally except on rare occasions the pedal will go almost to the floor. Once, it happened while hard braking after exiting the freeway. The other time, I was sitting at a railroad track waiting for a train to pass. The pedal very slowly went almost to the floor. After releasing the brakes, and depressing the pedal, they were normal again.
There is no loss of fluid. I recently replaced the front rotors. At that time, I flushed the brakes with a pressure bleeder.