Unless your MIL is an avid quilter, she probably will think it is supposed to be that way. It seems to lay nicely! I don't notice any quilting in the border. If you wanted to add some light quilting, it would be even less noticeable. If it is really going to bother you, take the binding (that you worked so hard on!) off and cut the batting out, but not quite to the seam and lay a new strip in. Hand baste it to the part next to the seam and then baste all three layers next to the edge. Re-apply the binding and nobody but the whole Quilting Board will know, LOL!!