It is normal for kids to be cranky and throw tantrums for a short period of time when they start new class/school. It is their way to express themselves or vent out as they may have bottled up some frustrations or other emotions since they are not familiar with the new environment to just be themselves during the day in class. Just try to talk to your child a lil bit more and see if she will eventually tell you about anything that may have bothered her.
May be her familiar place, teachers have been changed. she may take some time to get used for new one. my son took 2 months for that.