“I am a retired psychiatric nurse, adolescent unit.”
That’s very good. It’s also very good that your grandson is getting straight As. That’s a good sign. (Although one thing that I’ve heard of is that at some point, ADHD kids sort of hit the wall academically. It can happen at pretty much any academic level that the organizational demands overstrain their abilities, so keep your eye out for any signs that his academics are faltering.)
I think it all depends how good your relationship is with your daughter how much you can talk to her about it. Also, she may take it better if you share a (short, simple) book with her on ADHD. If you talk to her about your concerns, the biggest thing to bear in mind is not to say anything that sounds like criticism of her or her parenting. Keep the focus on your grandson and how knowing what you know about psychiatric issues in children, it would set your mind at ease if your daughter would allow you to pay for a private evaluation for your grandson. You can mention that it won’t be just looking for problems–you’ll probably get a very thorough evaluation of his intellectual powers, strengths and weaknesses, which could be very helpful in a variety of different ways.
Best wishes!