Did you read the Hardball transcript?
It's available here.
She was being hammered to justify something in someone else's book, a book that Mathews had not even bothered to read before the interview. That's hardly professional behavior for someone who considers himself a journalist, but given this part of his biography, it explains a lot about his behavior towards conservative guests:
Prior to entering journalism, Matthews served as White House aide and speechwriter to President Jimmy Carter and as a top aide to former Speaker of the House Thomas P. O’Neill, Jr.
