Zuko looks rather put off as he's suddenly bombarded with a bunch of questions. Especially since its in the past tense. It's kind of annoying and his nerves are starting to fray a little.

"A year and a half, and I don't know! I mean we did see some spirits there but nothing that would make this happen!"

That he knows of anyway. He really doubts the Mother of Faces and her wolf spirit could do something like this, but then he's not exactly the spirit expert.