If the only reason you send your child to daycare is to use it as a daycare, then I guess there's really not much of a problem, especially if your child is outgoing and plays with other children socially outside of daycare.
But if you send your child to daycare because you're using it as preschool then I think there actually is a problem. Part of the reason for preschool is to help socialize children who may not otherwise have much opportunity to socialize outside of preschool. It's often a good time to see if there are social development issues... so if your child's teacher is noticing and commenting that your daughter never wants to play with other children and always prefers her own company then the teacher is seeing a red flag.
And when a teacher sees a red flag then I would take notice and take it seriously. Ask her why she's bringing it to your attention and if she thinks any action needs to be taken. I wouldn't just blow it off, but have a conversation with your child's teacher. When my middle daughter was in preschool, we thought she was just shy and little behind... at her own pace as she always was... but we only had the comparison of her same-aged cousins and my close friends' children. Those were always very relaxed, unstructured events. Then when it came to a classroom full of other preschoolers her own age and she didn't participate and in actuality, couldn't participate, I had to pay attention to those teachers and finally admit and face my own concerns. We had her evaluated and discovered her Autism at that time.
Now at nearly 11 she's an amazingly wonderfully adjusted Autist, and she's made such strides. If I had dismissed teacher concerns... I don't know where we would be.
I'm NOT SAYING your daughter has ASD... I'm only saying don't blow the teacher off. Address this and see if there's a concern that you need to look into.