Don't have my books nearby, but it's an interesting grid.
It's 6x6, but (easily) constructed as 1.5, 1, 1, 1, 1.5.
Can't say I'm crazy about those salmon colors, but I do like the monochromatic coloring.
I 'got' how to create a similar block by looking at it, but your 1.5, 1,1,1, and 1.5 for the grid really 'put it in writing' very well. Thank you.