Yep, common mistake, you added too much water. You should have topped off to reach the target gravity, not to reach a volume level.
Don't worry though, all you've done is lowered the ABV a bit. This is a light style, so you probably won't even change the taste, it is just going to take more of them to get drunky!
Primary #1 - Midnight Ryeder (Midnight Wheat and Rye)
Primary #2 - Florida Weiss
Primary #3 - Kane-DOH APA (Honey Citra APA)
Secondary #1 - Downtown Flanders Brown (brewed August 2012)
Keg #1 - Raspberry Florida Weiss
Keg #2 - Cinnamon Raisin Cider
Keg #3 - NONE!
Bottled - NONE!