my son made me so sad

I dropped off my son at school this morning and he cried and cried yelling for me when they took him inside since he didn't want to go in by himself I am not allowed to go in the school I watched until I couldn't see him any more I was on my way to work feeling so bummed that I called off and went back for him I know I shouldn't have taken him out of school but he has never done this before it broke my heart so we are currently having lunch together his favorite Buffalo Wild Wings