I'm sure it has happened to others. Personally I didn't get tweeter problem but I had a defective woofer on my M80s and a defective mid-range driver on my QS8s.
What kind of amp do you have? Do you listen to your speakers loud? If you have something powerful, maybe you gave them more than what they can handle, if you have a typical AVR, maybe you drove your amp into clipping and that can damage the tweeter. Maybe it's just a defective tweeter, who knows? Did you check to see that the wire was still attached to the driver, maybe it came loose?
This kind of misfortune happen time to time but rest assured that Axiom always makes it right, so replace your tweeter and keep enjoying your excellent M22s.
