Air Pockets in the Deep Oceans

The Air Pockets have returned.
I created a 14w28b world in Minecraft in Creative mode. I was flying around when I found what appeared to be dark blocks near the surface of the Deep Ocean biome near Spawn. I flew closer to it only to find out it was a couple of air pockets starting 1 block below sea level and going down 2 blocks, enough for a person to fit into.
The water around them flows downward, but the water above them doesn't fill the empty spaces up.
Air "veins" aren't supposed to generate in places meant for water. What's going on?