Heva & Zacky - funnily enough DD was better if we drew out the goodbyes at creche. If we gave her one cuddle & kiss then the teacher took her she'd be hysterical. All we'd have to do was to go back in for one more kiss & cuddle and then she was fine!
They're all different I guess. I've worked with a couple of hundred children, all different ages and never experienced that.
(I hope that doesn't sound rude, I don't mean it like that, just saying, it hasn't been MY experience.)