He sees that frown - and he recognizes that feeling on his face. The feeling of being left out. Aang's memories of being excluded from his own friends, just because of the abilities he had as the Avatar, are still fresh.

"That's okay." He hops down from the air scooter, but he makes some motions with his arms to keep the scooter going. "If you hop onto that, it'll be like you're an airbender."