Just when you thought it was over, BART directors voted to head back to the bargaining table over a new dispute in the labor contract it signed with its unions just a month ago.

In October, BART management and union workers reached an agreement that ended a four-day BART strike and months of negotiations. However, on Friday, the Board of Directors at the San Francisco transit agency voted 7-1 in closed session to send the general manager back to the bargaining table with the unions to work out an issue over paid sick leave. According to BART, the agency was unaware that the contract that they signed last month included a family medical leave provision that would give union workers up to six weeks of paid time off each year.

"We've reviewed the chronology of events concerning section 4.8 and are convinced that it was never the District's intention to include the disputed Family Medical Leave Act proposal in the contract. We've also reviewed the preliminary costing of the proposed benefit. We are not comfortable with the potential liability that could result from the adoption of this contract provision," wrote BART in a statement, reports NBC Bay Area.

Under the current policy, BART workers have been allowed to take up to 12 weeks of job-protected leave to deal with serious personal or family medical problems or to bond with a newborn, but they had to use sick leave, vacation days or other accrued time off. Whereas under the disputed proposal, BART would now pay for the first six weeks of that leave.

BART called the error an erroneous liability that could cost the agency up to $10.5 million. However, union leaders are reluctant to return to the bargaining table over the discrepancy.  

"We're not ruling anything out, but we're not inclined to go back to the bargaining table," Castelli said, SEIU Local 1021 Executive Director Peter Castelli told the Associated Press.

Later, in a statement Friday night, he added, "Make no mistake, there was no confusion or glitch in the agreement. BART's high-priced chief negotiator Thomas Hock, Assistant General Manager Paul Oversier, and Labor Relations Manager Rudy Medina, signed an agreement that would allow BART workers time off to care for their family members with a serious illness."