First of all you have to put the fact she didn't call you behind you and drop it, forget about it, things happen and unfortunately it did MOVE ON!!
I am telling you this as a former full time teacher and now substitute. In the past six weeks I have subbed Kindergarten seven days at the same school.
First day drop off, your child is having a melt down. Is she (the teacher) suppose to ignore 19 to 22 other students who are having their first day of school and trying to figure out where they are suppose to be to come over and give your son personal one on one attention? When you the mother are right there. You the mother know your child better than she does and ONLY you know this isn't typical behavior. If he runs after you with you right there she isn't going be alarmed. Once the day has started and everyone is in class and the door is closed...he then opens it and runs she will page the office.
When there are tears they are usually acknowledged and then they allow the child to try and sort it out. Then they call the guidance counselor, if the child doesn't bounce back. Because when the school day starts it is going at a rapid pace. Morning announcements, the pledge, attendance, lunch count, and morning activity. This teacher has like I said before 19 to 22 other students to lead and start teaching the morning routine.
If he runs out of class. They have a plan in place to make sure he doesn't get out of the building. This isn't their first Kinder rodeo. And if they don't then I would be speechless.
I have had in the past weeks, students who cried off and on all day for various reasons, several runners, hitters, tantrum throwers, throwers of objects, and students who have to have their hands physically held any time we leave the classroom or they will run. To name the most common things that have happened.
While teaching a class of on average 21, five year olds, when any of the above happens and they are so disruptive you cannot continue teaching, they are distracting others who cannot learn, or endangering anyone (including themselves). We buzz the office and an aide, a counselor or administrator comes and yes, they go to the office.
In Kinder it is best to ignored unwanted behavior that not hurting anyone. If you rush to little Johnny because he is crying that he misses his mommy and make over him and coo over him. That guarantees anytime he wants attention he will do the whole crying routine again and again.
You DO reassure him everyone misses their mommy, but we are here to learn and have fun, he will see mommy later that day and then move on. If he continues you send him somewhere to compose himself a.k.a. the office. (He is probably equating being send to the office to calm down as being sent to the principle. Many kids go to calm down and come back. They are not in trouble they just can't stay in class and cry.)
I guarantee to you the teacher is not cold. She is using time tested techniques to help kids adjust and get used to school. Ignoring some behavior is one of those, sending them to the office to calm down is one of those, not acting shocked by the behavior is one of those...
Send her an email and express your concerns about the tough time at drop off being new to you and your son. That his running is also a new thing. Ask her to give you tips of talking with him at home about what to expect now that he is a big boy in Kinder. I guarantee you will find a lovely warm and wonderful woman who wants your child to succeed and will work with you to make that happen.
Kinder really is the new first grade. The amount of knowledge that this teacher has to impart to these kids in one short year is astounding. Give her the benefit of the doubt, back her up, and be her assistant in helping your son get the most out of this year.
One other thought from me is: when is his birthday? Is he a young or new five year old? If he is a young five it could be a much harder transition than if he has had six or more months of being five under his belt.
I know you want some mommy sympathy and outrage here. Having seen what I have seen in the past few weeks...give the teacher a chance.
FORGET about the lack of phone call...start fresh...be open to her...I guarantee if you have that tone of "you teacher have already made a bad impression" when you talk with or email her...she will pick up on it!! It will put her even more on guard. That will not help your son adjust it will make it worse.
Good luck!!