[Teito hasn't really been all that responsive to the headset as of late. He really just doesn't have that much to say to people. Especially people that he hardly knows. Sora and Riku are gone... So that really had an impact on him. Kid has a habit of withdrawing when people are taken away from him.
That has nothing to do with why he is out today. Today is different because he already has something planned. Not much, but the first thing he is doing is going back to return some things to the library. These "things" being a stack of books that look about as tall as he is.