You will get some theories, but I don't think you'll get documentation on that one.
A few years ago we had a prominent company rep. claiming "we must be using dull drill bits to cause their equipment to crack". What he didn't know was that we were using some brand new bits at the time...
Lately we've seen lots of those tiny hairline cracks on balls we've drilled, too (mostly one manufacturer). They have yet to affect performance, and they have yet to be bad enough to become a warranty situation.
For example, my teammate noticed his Roto Grip Wrecker had some the second week he had it. That was 4 months ago and the ball hasn't gotten worse, nor suffered performance-wise as far as we can tell. If it does actually crack then every manufacturer has been great to replace the ball.
Give it time. If they become worse you'll have a case with the ball company, but you never know which one gets worse while others don't.