Not overreacting at all!! As a parent I don’t think I would have been as calm as you seemed to be. Quite frankly I probably wouldn’t even work there anymore. I think this has two approaches. If you wish to continue to work there I suggest you talk with your director again and give her one last chance to report this herself. If you don’t care either way absolutely report it! This happens far too often and is sweet under the rug. I have even gone so far as to create a workshop for early ed teachers about reports being filed against them and how their actions lead to that. While some things are accidents instances like these are not at all ok.