I finally got around to purchasing a mat cutter --Logan Artist Elite 450, and cutting my first ever mat and backing board. I had a problem though, and something went amiss at some point. The mat's outer edge dimensions and the backing board's outer edge dimensions do not match perfectly, and I ended up with slightly smaller than a 1/16" over sized top/bottom borders of the mat. Do I have to start over, or is there some way to match the edges -- like a wood plane for paper? I know, you will not see the border difference after the mat is in a frame, however, our matts are being graded and I am one of the few people in the class who have never cut a mat.