[mrsmac]

I can't answer any questions with regards to loss but as a teacher I am surprised a preschool teacher would say that as how many pre school age boys sit nicely on mats??? I teach year 1 who are aged 6 and I have some boys who have taken a while to get the hang of it and its their 2nd year of school.
Without seeing your son myself I would hazard a guess that he is just acting like a normal 3 yr old boy. So much research is being done now on how boys learn and one of the big things is that they don't like to sit in a formal sitaution and thay are doers and like to be moving.
I am not trying to negate your feelings of loss just get rid of the guilt feelings cause I don't think you have done anything wrong.