Yes, it's happened, both to me and a guy I was fishing with. A certain variety of wooden darter with screw eye construction--tho the screw eyes probably weren't the reason the plugs cracked their whole length. The wood was.
Wise men speak because they have something to say; Fools, because they have to say something.
Got a 45 pounder on a yellow Gibbs 3-1/2 oz. Polaris in the canal a few years back and the bitch snapped it in half at the neck. ( no it wasn't a new plug either, it was vintage John P. Gibbs.)