Yes, totally normal. Most pullets that start laying are not fully grown, they will continue to grow as they age. So nature protects them by making the first eggs smaller. As she lays the eggs will get larger. After her first adult molt you will see another jump in egg size.
Don't be alarmed if you get some funky eggs either. Inconsistent coloring, huge double yolk eggs, even a shell less egg that just has a rubbery membrane around it. It's all normal while their system is getting the kinks worked out.