[Jason was already on the staircase to the attic to check the place's inventory when he just barely hears the thump. Neither Dylan or Sleeper have told him they were dropping by again.

Jason had purposely made the attic as innocuous as possible. Sure the attic window could be seen out in front but it took up much less space compared to the bar. Also, the entrances to the attic were either hidden or very unassuming. Outsiders shouldn't have a reason to go to the attic.

Maybe Hunter or Nico dropped by? Jason hopes it's one of them and a communication issue and not an intruder already. He silently heads upstairs, ready to summon his swords if needed]