the wikipedia article linked above talks about this, saying that the "...This method of transport does not involve objects in motion at speeds faster than light

the wikipedia article linked above talks about this, saying that the "...This method of transport does not involve objects in motion at speeds faster than light with respect to the contents of the warp bubble; that is, a light beam within the warp bubble would still always move faster than the ship. As objects within the bubble are not moving (locally) faster than light..."