Your quilt is beautiful and whether or not you take some of it out to correct the error should be determined by how you will feel about it after the gift is given-every time you see it. I think you have undertaken a wonderful thing to do for your grandmother. All of us who are grandmothers are very touched that you would undertake such a project for your grandmother. But remember that learning to quilt is a journey. Please do not be discouraged about your journey. Whether you decide to spend five or six hours changing it should not be a game changing road block in your journey. In my journey I have made lots of 'errors' (mostly that I wish I had chosen a different fabric for some or element or that I wish I had chosen a different stitching pattern to quilt) but I move on. I love to quilt and I want to grow so I keep quilting. I see lots of progress so I will keep going-I generally don't make the same error twice-I find a new one to make!