Some recent Rock Band DLC did not go so well. The Police Pack 01, and Brass in Pocket songs had a genre listing error and were hard to find in the game. The Rush “Limelight” song had some serious vocal issues.

How to re-download:
Xbox 360:
Navigate to the System Blade ( purple ), select memory, all devices, games, Rock Band, search for any of the listed songs (right trigger is a page down ), select the song with the A button, and then select Delete. Now either re-download from marketplace, or from the download history.

PS3:
The songs won’t appear in the store if you’ve already downloaded them, so you will need to re-download them from your download list.