My son is 9, he just had a very large bowel movement that was a bright pea to lime green. He has not had any foods with green, blue, red or purple food coloring in the last few weeks, nor has he eaten a great deal of green vegetables - he eats as few as possible in fact. The stool had some small light brown round stools attached to it, but he has never exhibited anything like this before. Should I be concerned?