I recently purchased a 2005 pontiac g6 with 11000 miles on it. So far, I love the car even though its my first car. For some reason though, when I switch out of park, when I put my foot on the brake for the first time after starting the car, the brakes kind of push back. Its almost as though there's air in them, but then I either just push through it, or let off the brake, reapply the brake and switch into drive no problem. Does anyone know what could be causing this?