I killed the Ender dragon, and it did everything that it was supposed to until it started dropping XP.  when it dropped the XP, it all fell in a line and (assumably) into the portal that takes you to spawn.  I circled around the portal and looked all around the end and didn't find any XP.  I then went through te portal since I figured it might be at spawn.  It wasn't at either my bed nor at the world spawn area.  I think it has something to do with the way the XP fell, but thats only a guess.