nervous breakdown

Well my very independant middle child had a nervous breakdown when it was time for me to leave the lunchroom. I volunteered to assist and she was with drawn during lunch and said she wanted to go home. No one in my family enjoys change but she seems to like doing her own thing. She begged me with tear filled eyes not to leave her at school. I kissed her head told her to put her lunch box in the bucket and play, tehn I turned around and cried all the way to the car as she was screaming 'mommy don't leave me here'. It was really awful! When she got home everything was fine. No mention of the incident at all. So do children manipulate on purpose or because they have uncontrolable fears?