Thanks Tim and bhplumber...
This is exactly when it happened the first time. I was coming down a long steep hill on the brakes. The 2nd time however, I stopped at a toll both. I suppose it still could have gotten hot, slowing down from 55-60. I will check this.
I got a crack in my front rotor as well. I seen that when I got the new tires put on. It's recommended that I replace rotors and pads on the front. Wondering if I should do them and calipers all the way around. That should be cheap...
LJ