Oh, these lines weren't easy to see, but now I get it

The "cubes" you are referring to is the "squares" I guess.

If your glass material doesn't have a map on it (which I guess you dont have), then it has probably something to do wtih the material underneath the glass. eh.. render the scene again without the glass and see what you get, take a look at the shader in hypershade and take a look at what color map it has. If it is wood and not wooden tiles, then I dont know why you got the unsuspected result. But I'm still a newbie.