Your recordings are based on a program's allocated time slot. If a program starts early or goes a few minutes late, those minutes will not be recorded. To ensure that you get the full show, including recaps from last week's episode or scenes from next week's, be sure to slide the timers forward or back when you set your recording preferences. You can move forward the start time by up to ten minutes and the finish time by up to an hour.
If you’ve already set your recording, just go to your Recordings pane and click on "Manage" next to the program's name. You'll see the option to record up to ten minutes before and sixty minutes after the program's scheduled broadcast time.