What would cause the cast iron part of the throwout bearing to break in half? Alignment problem or just a bad part? It's a Napa part, US made and about 5 months old with maybe 1,200 miles.

About a month back I got hung up in traffic for 45min or so and it started squealing/grinding with the clutch in, I figured the bearing went out, it had about 1/4" clearance from the fingers to the bearing so it wasn't turning all the time while driving.

The application is a '68 318/833 Dart.