After learning that Stillwater was looking for treasures to get back her own from the people that had taken hers away, Stephen decided to visit her and sell the flute.
He wanted to tell her that it belonged to captain Yolan of the Greenskull pirates, but it occurred to him that he was better of not saying anything.
He couldn't make Stillwater curious about how he managed to steal such a thing in the first place. What if she tried to kill him and take his pen? He would have no way of leaving this place if that happened.
Worried, Stephen gave no such information to anybody at all. However, surprisingly, the very next morning, he found out that the Greenskull pirates were dead and it had all been because he had been found as a traitor who was in collusion with the Rurian Kingdom.
Stephen knew he needed to leave soon now that Stillwater was most likely suspicious of him, but it wouldn't hurt to stay until the noon.