Oh empathy ... I have a sibling set who are occasionally like this at 4 and 6 ...IME it is just manipulative behaviour in an effort to get mom to prolong drop off cause the minute I shoo her out the door the tears turn off and they hop on into program all smiles .... I have implemented a 'you behave like that for your mother at drop off you must be VERY tired therefore your first 20 minutes of the day will be spent RESTING before you are allowed to go play' and it nipped it right in the bud!

Normally I too would look - has anything changed in program - peer arguments, social struggles resulting in consequences he might not like and so forth and if nothing in program I would than ask parent 'any changes at home' cause many things can create anxiety at being left even with a familiar and loved person - overhead an argument with parents, had nightmares, anxiety about talk about starting school and well list is endless?

Sometimes you can never figure out WHY and have to just approach it from 'not desirable behaviour in any event so lets put a strategy in place to stop it'! This is my sibling set - I am done trying to figure out what is going on at 'home' cause it does not MATTER regardless that behaviour of tantrum and throwing a hissy crying fit is just not acceptable so knock it off and use your words!