After speaking at an Obama event at the University of New Hampshire, but before going to a fund-raiser at Gerry and Elaine Schuster’s place in Boston, Bill Clinton paid a surprise visit to the Berklee College of Music bookstore Wednesday. We’re told the ex commander in chief bought Joe Viola’s “Technique of the Saxophone” (volumes 1-3) and also “Desperados: The Roots of Country Rock” by John Einarson. (Hillary Clinton’s husband has been known to play a little saxophone in his spare time.) Clinton happily posed for a few photos at the bookstore before hitting the bricks and heading to the Schusters for the event benefiting Brandeis’s Schuster Institute for Investigative Journalism. Guests, we’re told, included Mayor Tom Menino, Herb Chambers, Brigham and Women’s Hospital president Betsy Nabel, Bain’s Jonathan Lavine, and Brandeis president Fred Lawrence.