What the!!!!!!

I had something happen today that has never happened!the brass rod that moved the eyes just broke off in my hand after everything was painted, working great and ready to be shipped! A feeling told me to check the eyes and eyebrows one more time before shipping him out and when I went to move the eyes the brass rod just broke off in my hand! The top part is still connected to the eyes but about half way down in the neck it just broke off! Any suggestions why this happened?!?!?