Weirdly textured air

Ok, so I went into my Pixel Art World to resume my pixel art, but when I spawned, the place was black and blue (and green). It looks very weird, and I'm not sure if this is a bug or anything.

UPDATE: (It will be fixed once you re-enter the world, though. This just freaked me out a bit.)

UPDATE 2: I thought the bug was fixed once I re-entered the world, but it wasn't. I tried to place blocks and the thing came back.

UPDATE 3: I restarted my Minecraft and the bug seems to be gone.