Free exp in Scavenging with Beetles Quest

[HalflingPower]

For some inexplicable reason when going down the staircase in the scavenging with beetles quest I get like, 250-350 exp for absolutely no reason. I think this might be a bug, no pun intended.

[Jagged]

Same thing happened to me. Thought it was a DM. Gained 333 XP.