I've always heard that you should always have a mistake in a quilt (not a problem for me to accomplish) but I never knew why until I was reading the forward in a quilting book a couple months ago. Don't remember which one, so I can't quote it exactly, but it was along the lines of the Amish women always make a mistake in a quilt so as not to offend God at their attempts of perfection.
And your mistake is definately not one that takes away from the design of the quilt. Just think, it could have been of stars with one of the blocks flipped...go ahead, ask me how I know what that looks like. lol