Ever have a distributor rotor wear out?

[Sparky]

I was doing a routine check of my points a couple weeks back and I noticed the rotor was wobbling on the cam. It looked like the shallow molded ribs on the ID that made it fit snugly on the cam had worn down. I got a new one and it fits like it should. The old one was only a few years old and I’m sure it fit properly when new. Bad quality, or engine vibration causing wear?