I'm experiencing the same with the "Wild Blue Yonder" airplane block - just a smidge short in length on some of the blocks, others of same come out exactly. I have a sneaking suspicion it's due to a computer stating the exact sizes to cut instead of an actual person who would know to advise to cut a smidgen larger to be able to square up each block successfully.
I have tried opening seams that I had pressed to one side originally - that works on most, but sadly, not all. I will have to redo the tail section row, the last row, on some by cutting new pieces 1/4" wider to be able to square up exactly. The width of the block is overly generous, just not the length.
Hope I'm on the right track here. : )