How can you take on the mantle of perfection on something that you didn't make from the beginning? Don't get me wrong, I don't believe in putting perfectionism on yourself at any time. But when you are completing others work, it seems especially hard. If it is not perfect, maybe it you aren't to blame. Likewise if it is perfect, maybe you don't deserve the credit.
Enjoy the process. Quilts are love and love is never perfect.