If you have legitmate concerns and are not satisfied with the teacher's reply, speak with this year's teacher about it as soon as school starts. Let him/her know that you would like to have a meeting (an IEP meeting is for a student who already has an IEP). If the teacher brushes you off, let the principal know. I am an MCPS teacher, by the way. If a parent came to me, and I had no concerns, I would still have to schedule a meeting with the parent and members of the special education team. Either they can recommend testing, or help you understand why testing is not needed.
I know that push back happens in some schools, based on the responses from this forum, but in my school, I am motivated by what I believe is best for my students, based on my experience and expertise, and the rest of the administration/special ed. team is the same.