The wife and I arrived in Yellowstone Saturday May 19th and saw a sow gizzly with cub by the Fishing Bridge area, we stayed in our car as her and the cub crossed the road no more than 30 yards in front of us, that was scary enough as she was huge. My wife has a picture of her looking back at us with the cub in tow as they passed.
We had just left heading to Washington the day the mauling took place, my step son told us about it when we called him later that night. He works for the parks service in Yellowstone and from what he heard it looks like a case of being to close for comfort to a cub and momma didn't like it.