Board Thread:Naruto Discussions/@comment-24531362-20140904111518/@comment-24593592-20140909123029

Elveonora wrote: Where did you get that Hagoromo doesn't know what went on in the battle? He does, hence he knew Kakashi was talking about Obito

Kakashi mentioned Obito's name. He said "Obito's return was thanks to Naruto". Then the Sage replied "I see. I'll have to ask Obito about it myself". So he didn't know about his return.