Best way to remedy this?
 

I am making a quilt where the blocks start as strips, and you add smaller strips to the edges before cutting. For example, I start with a strip that is 9" x 21". I sew a strip on each long edge that is 1 3/4". I then cut these at 9 inches, and I will be adding a strip to the other edges after that, to make a framed block. Whether due to poor cutting, or not accurate sewing, some of my strips are narrower than others. They are supposed to be 11 1/2 " wide, but some are less. (I had poor lighting the night I cut, so I will blame it on that!)
So I am wondering, before I sew the strips on the other sides, is it better to go back and re-sew the narrow ones, using a slightly smaller seam allowance? Does that make sense? I feel if I do any trimming on the outer strips, that will show up as they will be slightly narrower.
I love reading this board, and maybe any answers to this will help others with the same problem. :o

go back and measure your cut and your seams to see where the error might have occured. Sounds like you will have to adjust somewhere depending on what you find

I think you have answered your own question. You need to resew them using a smaller seam. If the resultant seam is very narrow, use a shorter stitch length for a bit stronger seam. Correcting the problem now will make assembling the quilt so much easier.