Well, he might point something out, but I don't they can actually communicate. I am pretty sure neither Sigrun or Mikkel speak Finnish and vice versa.
So it appears to me that Lalli is more in standby mode. Observe and assess. I am pretty sure both Mikkel and Sigrun already presume that the place will be crawling with trolls. They may look like they are acting casual, but I am pretty sure they are also vigilant - notice for instance that there hasn't been dialogue since they have left the lobby.