If it were mine I would leave it I agree with Tartan and others once quilted you will find you are the only one that will notice it. It does not look that bad to me as I had to really look to see what you were talking about, it really does look good as is and I would not take a chance on maybe making it worse if it really bothers you how about appliqueing a horse shoe in that part and possibly doing 2 or 3 more in various places on the quilt Good luck and it is beautiful as is