Small pieces of concrete that fell from the ceiling of the Journal Square PATH station in Jersey City have caused minor service disruptions since Thursday. Small concrete pieces, described as the size of an apple, fell from the roof of the Journal Square station to the eastbound PATH platform at 2:15 p.m. Thursday, prompting officials to close the platform used by Newark-bound trains on the World Trade center line, said Seth Stein, a PATH spokesperson. No one was injured. The platform was closed as a safety precaution and single tracking service was operated while repairs and an investigation …