Castle suffered two minor strokes during the 2006 campaign, but fully recovered. Considering the general Democratic sweep of other offices, he won the election comfortably, but with a greatly reduced margin over previous years. Despite the increased Democratic sweep of the 2008 election, he, unlike many Republicans, managed to increase his margin of victory, winning over Democratic challenger Karen Hartley-Nagle by 23 points. Considering his moderate profile, popularity, and long history of Service to the state, his victory was not considered surprising. Castle appeared in the documentary, Keeping the Peace, which focused on Michael Berg's 'anti-war' campaign for Castle's congressional seat in 2006. It premiered at the Philadelphia Independent Film Festival in 2009 and won the Audience Award.