An impressive, detailed explanation on Jihadica, with links to interviews of those who had been in Iran and more:http://www.jihadica.com/abu-ghaith-a...ction-in-iran/

sources suggest that these men constituted a dissident faction within al-Qa’ida, one which in recent years had become increasingly vocal in their criticism of Bin Ladin, Zawahiri, and the direction that the latter had taken al-Qa’ida since the September 11 attacks.
It appears on my first quick read that Iran might have been a far safer place to be - from AQ - than anywhere else.