Kaesora question, spiders by library??

[Tann]

Posting here because most likely just necros and enchanters visit kaesora enough to know the answer.

Just started killing near the library, more specifically the hallway going down towards the library which has a group of 2, 3, and a pather that goes all the way up top of the hallway then all the way back to the library.

Issue I've had twice now, after clearing all 6 mobs I get attacked by a spider, after blurring it I watched it take the same route the pather does back up top.

Never been to kaesora before, is that a normal patrol mob?