Don't give up on the quilt just because of a few seams coming loose. If there's not enough fabric to hand stitch, then try putting a pretty applique over the bad area. Some really cute quilts have been made with kitty cats climbing all over them.
cat silhouette applique patterns - Bing images You can use your zigzag stitch and reinforce the areas. We've all had to make some "extreme" decisions so that the project is saved.
I see that you said you ironed the seams open. That wouldn't make it fray, but I find I like how the batting doesn't show when I iron my seams to the side. When I first started quilting, I ironed my seams open and found I could see my sewing threads in between each part of the blocks. I didn't like that . The thread doesn't always match as good as I would like.