Basically, the cobblestone stairs look pretty weird. Not sure which snapshot this first happened, though.

I was using the Custom World Gen, and i don't think that has anything to do with it, but, on the hotbar, the cobblestone stairs look normal, but when you place them down, they look weird. Really weird. Also, in a regular creative superflat world, i got cobblestone stairs, and they looked the same as the stairs in the custom world gen i did.

Edit So far, actually, i think it's all kinds of stairs that look like that, but with that kind's original color texture.

To reproduce it, just craft or get cobblestone stairs in Snapshot 14w33a