If I am understanding you correctly, you do not have a problem. Just continue on.
Where you may run into a problem, though, is with lining up the blocks. To avoid wonkiness, this is what I do. After adding a long sashing strip to the bottom of the first row, I turn the piece over and use a ruler and pencil to mark the block seam lines through the sashing. This creates "virtual" seams in the sashing strip. When adding the next row of blocks, I pin the actual seams to the virtual seams and ease or stretch as necessary to get those seams to match. Doing this ensures that the blocks line up when you are done.