NEW YORK — The NFL may be on the hook for more money than it expected if a federal judge can’t be convinced that its $765 million concussion settlement with more than 4,500 former players will be adequate to pay out benefits over the 65-year life of the agreement. The deal hit a snag Tuesday when a federal judge asked both parties to back up their assertions that the agreement negotiated over several months is appropriate. Philadelphia-based U.S. District Judge Anita B. Brody denied a motion that was …