Kardiac..I had the EXACT SAME thing happen to me. I was on an interstate and and RV cut me off..applied brakes and NOTHING happened. Then a light came on in my dash. I pulled off the interstate, FRONT LEFT brake was grinding metal on metal. Took it to the dealership..my front left brake caliper piston had been stuck closed and wore my pad all the way down to the metal. I was only at 40 k miles.