It's possible that the fabric that you think has developed a "twist" has actually undone the twist that was previously in it. Often fabric is not straight on the bolt, so when it is cut the cut actually goes slightly on the bias. This can sort itself out in the wash. To determine whether the fabric was cut on straight of grain, look at the threads and see if they are parallel to the edge. If they are parallel, and the piece doesn't look square, you can pull on diagonal corners to straighten it, at least somewhat. This article explains the process of squaring up a piece of fabric -
http://www.sew4home.com/tips-resourc...-fix-it-if-its