When your entire life is recorded, you never know what soundbite is floating around out there that will contradict your position. If you say something as a joke or that could be taken out of context, and then later claim to have never said it, suddenly you are a liar even though you didn't actually do anything wrong. It's possible that she just didn't want to get contradicted by some frustrated exclamation she had made years previously.
and yet, it's exactly this same person who will strengthen the NSA security apparatus that slurps up domestic communication wholesale, and saves it for all eternity. I hope you don't end up on the wrong end of a powerful person's anger, because you will go down the exact same way.
