Ask yourself this; how do you feel about doing more on the quilt? It's not just about how she feels, you know? If you redo the quilt but feel like you are being taken advantage of, but not saying so, then that will take it's toll on the friendship.
You really do need to have her over for coffee or whatever and have an open discussion about the quilt and the work that went into it. If she doesn't quilt herself, she might regard it as just a little sewing project. A lot of people don't realize how much time, effort, money and hard work go into making a quilt. You did more than "just a little favor" for her.
To ask you to redo the quilt without realizing the extend of what she is really asking of you is not fair. And it is the sort of thing that can eat at you unless you do have a real heart to heart HONEST talk with her about it. I think you owe it to both of you, and that very long friendship that you want to keep going.
You've asked all of us what we think, so let us ask you. How do you feel about taking on this chore, and it will be a chore? DO you feel you are being taken advantage of? Do you really feel like you would rather tell her thanks, but no thanks, once was enough? Could you suggest she have someone else add on to the quilt? Where do YOU stand?