R.K.
The skills you mentioned are quite age-appropriate. I think you need to know why the teacher shared the info she did.
1. Could she be reporting skills relative to a report card? That would imply no judgement, simply facts.
2. Is she giving you the impression that he belongs in another class this year?
3. Is she giving you the heads-up that she may recommend at second year at this level next year?
I would have another chat with his teacher to find out her impression of these skills relative to the pace of her class and her ability to work with children at different levels, and relative to how he will enjoy this year.
There is nothing wrong about being in a class with children of different ages and skills levels if the child is enjoying himself and learning well at his own pace. Then if he would benefit from another year at this level, as the older child, then so be it. However, if this teacher/class and he are not a fit, I think you might consider another option. All my best.