Map feature or bug?

[6Pix]

I was making another poster today, using Harvest as a background and as I was manipulating the camera, I noticed something in the skybox.

http://i.imgur.com/kJtj1Vv.jpg

Is this a glitch or a feature that I can disable? As far as I know, it hasn't popped up before, unless I just completely overlooked it. I verified my cache files and started it up again ,but it was still there.

Anyone have any ideas?

[Pte Jack]

I think that is the skybox itself, yup, does the same on my machine. Looks like whoever designed the map did not use seamless textures or missed the join marks. Not sure of a fix....