"As a journalist, I begin most interviews by..." ...talking about my cool pen and Gregg Shorthand for a couple of minutes. Well that's a great way to spend the possibly limited time your interviewee has to talk to you.
When hand-held tape recorders were new, I'm sure many journalists opened with "Have you ever seen one of these?" shortly before asking "Is it OK if I record this conversation?". Seems like a perfectly reasonable 30 second exchange to ensure that the interviewee is informed and comfortable.
When I do user interviews, I always try to talk a little bit at the beginning about something not directly relevant. It's especially good when I can offer something about myself; if I open up to people, they'll often open up more to me. It may look like a waste of time, but the better results say otherwise.