My wife called me today to tell me that the brakes started hissing inside the vehicle. She got home and sure enough, they hiss and feel spongy. If I hold the brake pedal down it gets harder and slowly goes all the way down. Brake booster? I have not changed nor messed with brakes, pads etc at all. Going on 60k miles and out of warranty. Taking it to the dealer tomorrow morning, hopefully get something resolved.