I was focusing on the blocks to the left and right of the current lesson and completely forgot about what was below it. Here's what it looks like in the mockup:
Wouldn't you know it, I had 2 of the same fabrics against one another. I suppose I could have left it but the perfectionist in me would have been bothered every time I looked at it so I got out Jack (the seam ripper) and made a slight modification. Here's the new block with the purple violet fabric swapped out:
It looks much better with the other blocks around it, don't you think?