fill enchantments require 16 bookcases in creative mode

So I went into creative mode because I fially decided to just mess around. Placed 15 bookcases and an enchantig table, loaded up on bottles o' enchanting, changed game mode and went to town.

When I finally went to enchant I noticed max level was 28. So I popped another bookcase down for a total of 16 et voila max level became 30.