Maybe some of your seams weren't 1/4". They must have been just a smidge smaller. This is what's neat about this quilt. You can trim a smidge on each side to even them up.
If you were making a whole quilt of these fabric strips alone you can sew 2 1/2 x 44" strips together and then measure the width, then cut your blocks to match. Chain sewing like that can make the project go a lot quicker.
Good luck.