First thought what oil was used/is being used.. Are you familiar with ZDDP, what it does & the fact it's been removed from most oil...
http://www.zddpforum.com/forum/viewtopic.php?f=2&t=7Second thought were lighter springs used during cam break-in?? There are plenty of other questions but those two are biggest...
Unfortunately flat cams are all to common these days & unfortunately when the lobes go they send metal particles throughout the whole engine... Often damaging pistons, bearings cylinder bores & sometimes cylinder heads...
Your whole engine really needs to come apart for a thorough inspection
Also I would strongly suggest a roller cam to eliminate the potential of this happening again