Yes, it is too short, but there is enough to get the exposition some light.
You can fill it up easily with some more imargy. Try to get into Zuko's phyche. You're rushing into your story, don't be afraid to stretch out the moments. And if you don't mind me adding: You abuse the word "Said". Every time someone speaks, the dialog is followed by the word "said", and although you were good to explain how the person spoke, there are other words out there.
Such as "commanded" in the last sentence"