Linda Ronstadt did the same thing at Wolf Trap earlier this month. I guess she thought annoying much of her audience was her civic duty.
The biggest excitement of the night, by a long shot, came when Ronstadt then dedicated her encore of “Desperado” to filmmaker Michael Moore, kick-starting a boo-cheer competition throughout the venue that drowned out her singing and left grown-ups in tuxes and evening gowns yelling at each other on their way to the parking lot.