I just bought a "new" certified '03 Corolla LE and have experienced the following issue. Sometimes, when I have been at a stoplight with my foot applying normal pressure to the brake pedal (which operates firmly & without sponginess to stop the car in a normal fashion), the pedal will sink down about 2 inches without touching the floor. This has happened about 4-5 times in the past 10 days. The service guys did not find any external leaks & can't duplicate the issue, so I've been told the master cylinder is operating "as designed." Has anyone had or heard of a similar problem? Do I need to bleed the system? What if I do that & it doesn't solve the problem? I love this car, but am worried about this brake thing.