I have a 2007 Honda Civic. A few months ago I noticed that I had to push the brakes down harder to get the car to stop. It started getting worse, getting to the point that when I would start the car and put it in reverse, flooring the brakes would have almost no reaction, and then they'd kick in and I'd be able to stop. This only happens sporadically.
The brake pads are fine, the brake system has been flushed and the master cylinder was replaced last week. Today as I was backing up (right after starting the car), I put the pedal to the floor and nothing happened for about half a second.
While driving, the brakes seem fine. This is typically an issue at low speeds (parking, etc.).
Any ideas as to what it could be?