[t walgamuth]

I had a similar thing happen on my Formula Ford autocross car about eight years ago. The hub had cracked but things were still together. I did not notice anything unusual until the wheel came off. Like in your case the caliper on the disc had been holding on and did so until the center came out of the rotor... and I spun to a stop.

The hub had actually fractured and came out in five pieces.

No fun!