The opening night gala at the San Francisco Symphony was going off beautifully, with 2,700 patrons enjoying the glitter and glitz of the evening, not to mention some fine music. Over 1,500 supporters had dinner at Davies Symphony Hall, and the orchestra was reportedly in top form for the performance under music director Michael Tilson Thomas. And then, in the middle of Stravinsky’s Firebird Suite, someone pulled the fire alarm.