Danny Masterson Prison Transfer Wasn't Result of Attack, Threat

Danny Masterson is settling into his third prison in two months ... and TMZ has learned why he's been on the move so much. Despite reports claiming concerns for Danny's "well-being" were behind his recent transfer from one of California's worst prisons to a more humane facility, we're told that's not quite the reason for the move. Sources with direct knowledge tell TMZ ... there was no attack on Danny at Corcoran…