Hi there. First, I want to tell you that very very many children have a rough transition to kindergarten. It's a tough year for a lot of children. I would keep that in mind and just sort through the problems looking for root causes.
It is very true that gifted childen have problems in traditional classrooms sometimes. That is something to consider. Have they benchmarked where she is at?? That is helpful in determining if this is contributing to the behavior problems at school.
I think you are vey smart to be investigating root causes with a behavioral therapist. I want to add something else into the mix of what you might be thinking about. That is sensory integration disorder. It looks very much like add/adhd as both are nervous system issues. Does your daughter have a lot of issues at home as well (as add/adhd must show itself in more than one place). Sensory is more likely to surface in school only or under certain circumstances such as crowds, parties, etc. We see an occupational therapist for my sons sensory needs which has been a god send. They work on behavioral modification and sensory activities that work directly on slowing down his nervous system and helping him stay organized and focused. Something to think about.
You sound like you are on the right track to look at why she is acting out in school. It could possibly just be adjustment, immaturity as well.
When is your daughter's birthday by the way? Is she young for her class??
Also, any type of punishment for undesirable behavior must take place at the time of the offense. Punishing after school is too late. So you will need to work with the teacher for what they are doing when the deeds occur.
Lots of luck to you.
Have you ever had her evaluated by a child psychologist or psychistrist? There are a lot of red flags going up for ADD/ADHD, and actually, most children with ADD/ADHD start showing signs when school starts, as it is really the first controlled learning environment. It's also very typical to see a child with ADD act out, as they become very frustrated in the classroom setting.
That would be my recommendation, have her evaluated for that, or any other possible issue. If she is suffering with ADD, you will learn techniques to help her learn properly, the school will become involved also, to help her learn, with the challenges she faces. You will also learn the proper way of dealing with any related behavioral issues. Most ADD children will show improvements in their behavior, once the ADD is addressed properly.
Best of luck!