AP Photo/Susan Walsh

D.C. Schools Chancellor Michelle Rhee has been basking in the limelight since she announced that an agreement on a teachers contract had finally been reached. At a hearing before the D.C. Council today, though, her celebratory mood was quickly dampened by revelations that might endanger the whole contract.

The Examiner reports that at a hearing on Mayor Adrian Fenty’s 2010 budget today, Rhee explained that part of the teacher raises contemplated in the new contract would come from a $34 million surplus in the schools budget. Of course, various members of the council were quick to inquire how the school system could be running a surplus now, when just last fall Rhee justified the dismissal of 266 teachers due to a $43 million deficit. According to Rhee, the surplus was uncovered because a previous budget estimate mistakenly used $81,000 as the average teacher salary, about $15,000 more than it actually is.

Predictably, various members of the council were shocked to hear that the 266 teachers who had been RIF’d — though Rhee did controversially argue that some were let go for more nefarious reasons — may well have lost their jobs for what now seems like bad math.