A message from President Obama and first lady Michelle Obama, apparently signed by the president with the wrong date in the visitors' book during a tour of Westminster Abbey on Tuesday. (POOL/REUTERS)

Then, he goofed. He added “24 May 2008.” It’s not clear if he was having more fun on May 24, 2011, that he had three years ago on the same date, when he was in Puerto Rico for one of the last Democratic primaries in his race against then-Sen. Hillary Clinton.