I have done this numerous times. I’ve never had a problem just restitching a wider seam . My miners still lined up, I have never had to remove any previous stitching unless the original was too wide& I wanted it narrower

Thank you for all your suggestions!

Just though I’d let you know that I have managed to widen the seam successfully.

As all of your comments made sense to me - even though they differed - I decided to make a sample from spare fabric and binding to see what would happen. I deliberately stitched it too narrow then stitched again a little wider and it worked. So I did the same on the original quilt.

I remembered when I first started quilting I used to mark a 1/4 inch line on the binding to keep myself right - might start doing that again.

Thanks for letting us know! Sounds like it worked out for you