Could there be trouble brewing behind the scenes of the world’s biggest singing stage? The American Federation of Musicians has filed a lawsuit against American Idol producers. The damages sought by the union is currently unspecified.

The suit claims that American Idol Productions Inc. and Tick Tock Productions Inc. (a subsidiary) violated a bargaining agreement by underpaying musicians. According to the terms of the contract, musicians receive royalties for re-runs.

Since 2007, however, the soundtrack for past episodes was cut out and new musicians hired to record new music for episodes of American Idol Rewind. The musicians’ union was not informed of this decision.

So, far the powers-that-be at American Idol have offered no comment on the suit.