If you’re planning to attend the San Francisco Symphony’s opening gala concert this week, be sure to take note of the second stand of violins, where Mark Volkert, the orchestra’s longtime assistant concertmaster, will be playing. From one perspective, Volkert’s appearance on the stage of Davies Symphony Hall isn’t that newsworthy — after all, he’s been a stalwart presence since joining the Symphony’s ranks in 1972, as a Stanford undergraduate.