WordPress Multisite with subdirectories - why did it add a bunch of numbers? e.g. mysitename10774940

I signed up on my new Multisite with Facebook (using the Ultimate Facebook plugin) and entered "e" for my blog URL. Now it's showing me "e1077494009" as my blog URL! ( nomjoy.com/e1077494009 )

How do I make it just nomjoy.com/e ?