No, I think it's the pattern. You can tell, though, that the white areas will turn by 90 degrees every horizontal row (see how the single white square is on the sides in the center, but will be at the top and bottom in the next row when you add more blocks?). That might be interesting, anyway. I think it looks nice
I think the problem is that the center of the IC block is 5 squares across, an odd number. Because of that, you can't ever put two blocks together and get the same center (will always be even: 2*x=even #).
If you wanted to "fix" it, you could leave off the outermost squares on a block, then make a sashing to finish it off. You could probably work it so that one of the rows of squares that you take off would make the sashing. Then you'll have 2*2+1=5 squares across and the intersections of the blocks will look just like the centers of the blocks.