This nice CATO is probably a result of incorrect storage.
Warren had purchased these about a year ago and stored them on a
shelf in his living room. The package had been opened and he
thinks that the humidity, heating and cooling resulted in an unstable
condition. He was lucky, the rocket was undamaged. Live
and learn, by the way he still has one left.

Here is a picture of the recovered D12 and the remaining one from the package.

If you look carefully slight bulges are present on the remaining D12.