http://i.gyazo.com/30c04a228f893f07d52b236b9fc0dc6c.mp4

This only happened when just end stone was in my inventory. Interestingly enough, it also happened with End Stone Bricks.

I further tested this and it only happened when just End Stone was in my inventory and nothing else: http://i.gyazo.com/21ea0a5ce7e6d4083cee51410ef2d645.mp4