Steel belts in the tire can break without obvious signs untill complete failure occurs. If you can, lift the wheel and spin it watching the treads in the tire and see if the groove stays true. That is, no in and out move ment as the wheel spins. If that looks ok, then watch from the side for up and down of the outside tread for out-of round tire. Broken belts make the tire worse over time, so you may have to put some more miles on before it actually shows.
Rod, July 2009