That makes a lot of sense. I thought it was maybe that they are horrified by the smell and are running to escape it...or are surprised that that came out of them.In the wild, the times that they are the most vulnerable to predators is either when "going to the bathroom", or when they are mating... That is why these things are done quickly, and out of there! That is also why it is good to have the box in a more secluded space, where they feel safer...
My lil' girl is "shy".