The past week saw two major music directors – Boston’s James Levine and the London Phil’s Kurt Masur – fall ill on the eve of a major tour. In both cases, podium replacements were quickly named, and the tours went ahead. But what about those substitute conductors? Were they just sitting around waiting for something to do? Not a chance – Marek Janowski, who stepped in for Levine, was in the middle of a two-week conducting stint in Minneapolis when he was asked to make a one-day, 3000-mile detour to conduct one of the most difficult programs imaginable at Carnegie Hall. Meanwhile, Minnesota’s own hometown conductor, Osmo Vänskä, scrambled to reach Southern California to take over Masur’s duties.