Musicians were stunned and saddened when Peter Stumpf, the principal cellist with the L.A. Philharmonic, revealed that the orchestra's 320-year-old Stradivarius cello had disappeared from his home in Los Feliz. I wonder what they think now. You see, the $3.5 million instrument wasn't purloined by an international theft ring, or even taken from inside Stumpf's home. He left it out overnight on the back porch, and it was swiped by a kid on a bike. The kid and the Strad are still missing, but the cops have a videotape.