Several years ago I had something odd happen. I noticed that I had dificulty writing certain letters. It was only letters that had a radius or curve in them and only curves drawn in certain directions. To write the top part of the S, my writing speed drops to maybe 25% and I have to actually think of the shape. Once I finish the top part of the S, I pop back into normal speed. There were other letters and I think the 3 was a problem as well, but not any longer. The top of the S is still a problem.