Sandra Bullock has David Letterman to blame for her being late to a cocktail party at Monkey Bar hosted by director Paul Haggis to celebrate her Oscar nomination for “The Blind Side.” Bullock was on set during Monday’s taping of Letterman’s show when stage manager Biff Henderson injured himself after awkwardly catching a football thrown by the host. The mishap delayed taping, as Henderson was taken to the hospital. Bullock finally arrived at the restaurant with her own football autographed by New Orleans Saint Super Bowl hero Drew Brees.