Media more skeptical of Pelosi than CIA

Greg Sargent notes that the media has been far more critical of Nancy Pelosi's claim that she was never briefed about waterboarding than they have been of the CIA's claim that she was. As Greg notes, it's fair for the media to be skeptical of Pelosi and push her to prove her case - that is their job. But then why isn't the media pushing the CIA, questioning the CIA, just as hard?