DENVER—Did you think Sasha Obama talking to her dad while beaming from ear to ear was cute last night? Me too. It turns out she and her older sister Malia didn't know Barack Obama was going to be on screen. Jim Margolis, a Democratic media consultant who is part of the Obama campaign, told our Michael Barone (who's tied up on the floor of the convention) that he told Michelle Obama before she went on stage not to tell the girls their dad would be joining them by video. I guess media consultants know just the right way to the hearts of America: surprise a seven-year-old with her daddy.