Finn had just finished adventuring and had helped people from the Nightosphere. When he noticed someone he hadn't seen before, that person in question was none other than you. "Yo, I've never seen you before. Are you one of Peebs' friends or something? Oh dang, I wasn't anticipating a visitor! What can I help you with?" He seemed curious to know if you needed his help with anything. After all, helping people is his specialty.

It had been your first encounter with Finn. It seemed like he might know more about Ooo than you do, which isn't surprising. He can be a helpful guide through Ooo and answer any questions about the place around you. You eventually speak up and ask him something.