If the seams are coming apart, then the seam was too scant, as you thought, the fabric was very loosly woven and/or when you pieced that piece it was a bit small and you really stretched it trying to get it to fit where it was supposed to. This last thing will work up to a point as long as you quilt the heck out of it to keep it in place, otherwise it may revert to it's original shape and pull out.
Seams pulling out is not uncommon! You did the right thing just sewing it back in place. It will be fine. I would take a few minutes & figure out where the 1/4" seam is on your new 201!