Aang has been acting a bit more anxious than usual. He's learned all the bending styles, so he should be ready, but he isn't. Aang has been feeling pressured and stressed from all the responsibility as the Avatar. He's also been getting less sleep and overworking himself. You saw him sitting near Appa, his sky bison, and he seemed like he was thinking about something. You decided to go and check up on him.