I bet he was responding to a DM that came in via SMS on his iPhone. I've done this before: You get a text notifying you of the DM. You immediately reply to the

I bet he was responding to a DM that came in via SMS on his iPhone. I've done this before: You get a text notifying you of the DM. You immediately reply to the text thinking that it'll automagically send it back as a DM.