If she generally has difficulty engaging with people and other environments, then you might have some red flags, but if it is just at school, then I would look first to a mismatch between the school and her needs before assuming anything might be wrong with the child herself.
She's an entirely different person at home. Her plays at home are mostly interest-led, rather than regimen-led. While school is mostly regimen-led, and DD doesn't always want to do what the rest of her class is being asked to do at a given point in time. She ends up choosing to do something else, and plays in her mind.
