It is an offline rebuild. I wonder if there was something that might cause it to be blocked but I wasn't the one that stopped the job at the time so I was able to check it out while it was still running. By the time i was notified of it, there wasn't any open transactions or any locks.

The job runs at 3am and is usually done by 3:20am. I'm not sure what caused it to run that long. Is there any other way I can figure out why the job took so long to run? Or is it pretty much nothing I can do at this point to find the cause?