Dionysus listens, growing more and more worried as Laertes goes on. So it is something serious.

"I know several people who might be able to do what you're describing. The nightmares and mind powers part, anyway. But I trust I would have recognized them, had they been present at the party. I -- I still want you to be careful, Laertes." The last thing he wants is Laertes getting returned to the tale from which he comes. That's not even getting into the implications regarding 'mind powers' that Dionysus is all too familiar with.