I have a friend who leaves 1/4' of backing and batting beyond the quilt top when she trims her quilt. This extra batting and backing adds bulk to fill her binding. I've tried it a few times and liked the results when I'm doing a traditional binding. It doesn't work when I do a faux piped binding, since you machine sew the binding onto the back and pull it to the front. With Faux Piped bindings, the extra fabric from the seam allowance on the piping fills the binding nicely.
In the end, it's your quilt. You have to decide how much you care about the judges comments. After all, she's just a person who has some knowledge about quilting and has been asked to offer her opinions...I've entered many quilts in the local county fair open class and won lots of ribbons. My mom encouraged me to enter a couple in the MN State Fair last year, and while the field was much more experienced and vast... the only comments I received were pretty nit-picky about bindings, etc. Those comments don't depreciate the value of the quilts to me at all. You have to decide how much you care. I've decided I don't.