She did give back the extra fabric, but I didn't really look to see if she'd used it. Nothing looked amiss at the time. Live and learn.
I thought about taking out the stitching, but I don't have enough batting. She thought about the batting carefully, and used expensive wool batting because it was the most flexible (and it IS very warm). She gave me the extra batting, but to do all of that ripping and piecing seems formidable. I think I'd rather just make another quilt.
I still like the quilt. It's just too small for the purpose I had in mind when I made it. Besides, it gives me an excuse to make another one! I might even do this one again as those fish blocks went together pretty fast.