Is this unusual?

TCM and I were busting caps the other day, and my FAL stopped ejecting its empties.

After looking the rifle over a bit, I saw threads where threads did not belong. Through a crack in the gas regulator ring.

Now how often does this sh17 happen?

We figured out how to get the split one off, and there is no shortage of replacements online. But is this gonna happen again?

UPDATE: often, if the ring was made by Imbel rather than FN, and mine was. The finish that Imbel applies insulates the ring from the spigot it is threaded on to. The ring heats less quickly than the spigot. The spigot expands, the ring doesn't. Pop.

I'm told lapping compound will remove enough of the finish that a new regulator will be my last.