Not sure about the "critical mass" theory above, but the fact is they didn't heat treat it properly, or pay attention the quenching process when producing the billet. Metal has many different "structures" it can end up in, and if it is aluminum, then aging can come into it as well. Either way, they should replace it and ask for it back for lab analysis. Dunno whether they will or not though. Best O' Luck to ya! Let us know how it goes.

--Air