Torsion Bar Adjuster

Has anyone had a Torsion Bar adjuster break while driving down the street?

My passenger side just made a wicked pop. Luckily I was basically pulling into my driveway. The threads seem to have stripped out of the block itself, found the bolt on the ground and it is otherwise unharmed.

I assume this isn't common. Any idea's as to why it would randomly fail? I'm thinking it's just old.