Why was last nights episode of "The Office" a repeat?

Did I miss something? Normally I know what's going on with the show but for some reason it was a re-run :-(

Yes, it was the episode where Michael outs Oscar.

A lot of stations will air re-runs if the other station is running something they can't compete with. A good portion of the US is watching the World Series right now. Not positive - just a guess.

There aren't enough episodes in a season for the number of weeks. Therefore, they throw reruns in to stretch the episodes out to fill the season.

November sweeps starts next week and the World Series is still going, so most networks are probably running re-runs and saving new episodes for next month

They will be back next week. World Series is taking a lot of viewers away from regular shows.

I watched it but as far as I know it was not a rerun

I agree with what the other answers that said it was because of the World Series. There were a lot of re-runs on that night, as well.
There won't be any re-runs coming up in the near future, thank goodness.
These are the next three episodes:
- Nov. 2: Diwali
- Nov. 9: Branch Closing
- Nov. 16: The Merger

Don't know any passed that.