The MTA says all service is running normally now, but, earlier, a switch problem at 59th Street/Columbus Circle caused delays with the A, B, C, and D lines. The trains were diverted, with the C going express between Canal and Columbus Circle and the B and D running local between West 4th and Columbus Circle... we even heard that the B and D were running on the northbound N/R line.
Because these delays affected the A, B, C and D, we're pretty sure that's why some other service was impacted One F train rider told us that his train waited 10-15 minutes at EACH stop during his commute from Brooklyn to Manhattan. This must have been fun for commuting students.