Stupid whitebelt question: Every now and then I get bad mat burns on my feet. Now obviously I would expect this to happen once and a while, but it isn't consistent. I can go weeks and months without getting it, then out of nowhere after a single class my feet are torn up, usually in different spots. This leads me to think on those days I'm doing something incorrect that I'm not pickup on? Or am I reading too much into it? This is actually the best it's been after one of those days, it's usually a lot worse. Thanks.