Here is the story I heard. At Saluc, there is a very strenuous QA process. Sometimes Olga, the inspector" whacks the balls too hard which dislodge the number from it's final resting play.
Those balls could all be infected with aramith worms. They attack the numbres because they are a little softer and make for better "nesting". To verify this, take the balls to a vet clinic and request an x-ray. If found, they will inject the ball with the proper anitbiotic and the the ball will eventually readjust itself.
No need for thank yous, I am just happy to help.
Dan