Its fine.
My son is/was a napper, even in Kindergarten.
He would not and could not eat, if/when very tired. He would just pass out sleeping until the next day.
My daughter as well, if she is tired... she can't eat.
Going to school, all day is very tiring for a young child.
In many ways.
They need rest when they need rest.
Its okay.
My kids are like that too. Even my 9 year old, last week passed out after school and napped while doing homework.
She needed it.
When my son is going through a growth-spurt, he has been known to sleep for 14 hours straight. And I didn't wake him, nor for meals.. he just slept. Doc said its fine.
The Teacher, should be telling you if she napped or not in Kinder.
My son's Teacher in Kinder, would send a cute little note home with the child, for the parent, saying if their child napped. The kids didn't HAVE to nap, but for those who didn't it was quiet time, the room was darkened etc.
Also, some kids get tired and sleep more if they are getting sick.