Found this in the nud log. Maybe I should ask it here since it seems to be from peercoin code: Exactly how does my minter get a stale block? Is there anything I can do to minimize it?
if (pblock->hashPrevBlock != hashBestChain)
return error("PeerMiner : generated block is stale");
Looks like your previous block is not the best chain anymore.
Thanks. You are right. There was a reorg just when the minting happened.