There are no quilt police. Small pieces of cut fabric are important to keep the size when pressing. ANYTHING with a bias edge will stretch. If your in doubt which is the bias edge, hold the fabric selvage to selvage and try to stretch. Then try to stretch the other direction at a 90 degree angle. It will stretch more. Now try to stretch it from corner to corner - there is your bias. This is the most important sewn seam to PRESS never iron. As others have said, as long as you square you fabric and cut correctly you should be ok. I also use 'sizing' when using the iron. It gives a little more stability. Good luck.