I've seen this happen a few times with my BF. As he's dozing off, I can sometimes hear little snatches of conversation (he talks in his sleep). When he wakes up he'll tell me about talking with one (or both) of the others. Usually, it was a helpful conversation.
I wonder if it's easier to communicate then, in semi-consciousness, because the walls around "standard" reality get relaxed and we can touch things that normally get filtered out?