When creating a singleplayer world. Title screen flickers in

Whenever I have created a new world since 1.3 I see the title screen flicker once or twice briefly before I'm spawned in the world.

Reproduce by simply creating a new world.

I have recorded a soundless video documenting it.
http://youtu.be/0QYPwuoGom8

Sorry if this is a duplicate, I couldn't find anything matching this.