Was last weeks show for the office just a re run or what was the theme?

Answer 1

It was a rerun of this season's first episode, "Gay Witch Hunt."
This Thursday's is a new one which is called "Diwali"

Summary (NBC): Michael encourages the entire Scranton branch to support Kelly and attend a local celebration of Diwali, the Hindu Festival of Lights. As Ryan nervously faces Kelly’s family at the event, Michael, new girlfriend Carol, and the staff sample a range of Indian culture and cuisine. Meanwhile, Andy convinces Jim to turn a late night of work into a drinking game.

Answer 2

It was a rerun. I can't wait till tomorrows new episode.