Are you a smoosher? Do you press down when you measure your gauge? It can cause real problems, especially with bulky or lofty yarns. I measured a bulky swatch twice. In the top photo I just placed the swatch gauge on my knitting and measured - 5.25 stitches to 2". I measured the same knitting again and pressed down. Yike! 4.25-4.5 stitches to 2", that would give me trouble if I needed to have a specific gauge for a garment or anything I wanted to fit. I press down sometimes when I measure gauge, thinking that it would keep my swatch from shifting - never again!