A lot of people are missing the point, debating whether this was reasonable or not.

Mark got away with telling Congress ~"we don't share with third parties" and now they're saying Blackberry's not a third party.

If it's all okay, why didn't Mark come clean? and tell his Congressmen? He had a chance to explain this arguably-harmless behavior, but he chose to sidestep it. Why? Did he not understand the question?

It's fine that this data-sharing is maybe reasonable. It's not fine that Mark withheld this from Senators. This is exactly what they were asking about, and given the chance to explain, he chooses silence. He gets to avoid the public debate while the techies argue amongst themselves.