The Futon Critic has labeled last night's fast overnight ratings as "unreliable," from what I gather, TAR may have been interrupted or pre-empted on the west coast.
I do know that on my local CBS station, Undercover Boss finished on time on the east coast feed, then I switched to a cable channel to watch the Borgas, and when I switched back to CBS when that ended 10 minutes before the hour, CBS was reporting sources on the death of bin Laden; that is what leads me to think that the west coast feed was pre-empted.