When I make a mistake that sounds that large (a picture would have helped us), I would grit my teeth and fix it. Otherwise, it feels like failure to me - an undone thing. To say that the recipient is too young to notice or that he won't notice because he's a male feels disrespectful to me. Not only that, remember that the young have older people in their lives, like parents and grandparents, and males have women in their lives, like sisters, wives, moms, and grandmoms. If the error really is large, I think you might feel better if you fixed the quilt. From one who has been there ... several times. Good luck!! Would love to see your finished quilt! What a caring thing for you to do!