You can straighten uneven grain on panels by stretching them on the bias, both ways,
before you cut out the blocks. Snap the fabric when you have it taut. Then check to see if the grain is more squarely situated. They are all printed straight, but in the winding and bolting of the fabric they get skewed.
Donna Jordan shows how to do this in this video at 1:54.
https://www.youtube.com/watch?v=UGt6_pWo6zs