Last season, the Philadelphia Orchestra’s new principal cellist, Hai-Ye Ni, was told that she was not being granted tenure by the orchestra, and would not be brought back for the 2007-08 season. It was a major blow for a cellist who has enjoyed a successful solo career and who had quit a section job with the New York Philharmonic to come to Philadelphia. “But a grievance was filed with the union, lawyers were called, conversations were had, and now she’s back. Music director Christoph Eschenbach has agreed to extend her stay, giving her another year of probation.”