The thing you want to keep an eye on is if she is suppressing who she really is to "fit in" (which we were starting to see in DS as young as 3). But if she is happy and engaged there, I would not worry...
She is a submissive and sensitive child by nature, and often defers her own desires to please others. I suspect she has some pretty pronounced gifts in intuition and empathy. This is wonderful, of course, but it does present challenges in knowing who "she is".
Several times, at her school I have witnessed this. One example. They children had taken books off the shelf and another tried to take the one my child had selected away from her. The teacher intervened gently, and walked away. My daughter waited until the teacher was focused on something else, slid the book over to the other child, and went up and got another book. She was about 19 months with this occurred.
We were watching ice age last night and the "squirrel" got hurt and she turned to me and said "poor squirrel. is ok mommy? ok?"
sooooo... that really presents a challenge to me as her mom... how do I know if she is even willing to articulate assertiveness? she does with me to an extent, but I doubt she does there. She seems happy to go, though.
