Moffat loves having someone use the words Doctor Who in each episode - a sort of meta-narrative on the show. The modern over-usage of meta-narrative can get old at times and Moffat seems to enjoy it.
I don't think it's just self-indulgence. We now know that 'Doctor Who?' is The First Question (the question that must never be answered!), and that the answer will cause Silence to fall... It's a giant flashing reminder of DANGER, and the story to come.