There's no law that states you must sew the binding to the front and stitch to the back, I know people who do it that way. If you're satisfied with how the binding comes out, then that's all that matters. As for the possibility of a person receiving one of your quilts and them "noticing" that you sewed it back to front, versus front to back, they most likely don't care, all that they care about, is that you cared enough to make one for them.