This is very common. I agree with all that the other ladies have posted. It is partly an attention getting thing because they miss the parent and partly because the parent has not established proper discipline with the child and partly because of the transition. I have one who will run into various rooms of my house on his way out with mom...she cannot control him. Then I hear his tantrums as she tries to wrestle him into his jacket and boots. He's 2.5. If I am there, he doesn't do it, but I have a basement daycare and parents have to come in and take their kids up and out so I cannot escort them to the door as I can't leave all the others alone.