When I logged into my creative world that was created with SuperFlat, void particles are appearing and the sky is dark at Y = 4. I re-started Minecraft using 1.6.4 and the problem goes away. I've attached two pictures showing what I am experiencing.

What I expected to happen was...:
Since I am above the bedrock, no void particles should appear.

What actually happened was...:
Void particles appear and the sky turns dark.

Steps to Reproduce:
1. Create a new world using the default settings for SuperFlat. Needs to be in the latest snapshot.