I think Bambi mentioned this up there somewhere, but if you talk to Laguna on the Ragnarok in the conference room
, he says to Squall that he wants to talk to him more when everything is all over. He also tells Squall he will understand if Squall doesn't want to hear any of it. But anyways, yeah, from that I agree with others that he probably told Squall everything after the final battle was over.
just before ramming into the Lunatic Pandora to face Adel