My son was diagnosed with learning disabilities in first grade. His kindergarten teacher was the first to tell me that he wasn't "getting" certain things. We tried lots of things at home during that kindergarten year to help him and spent a lot of money on reading programs that didn't solve the problem, but it was a first year first grade teacher that had the insight to tell me that she thought it my be a learning disability. We had him privately tested and found that he had learning disabilities across the board. His IQ was extremely high, but his performance was way low. It's the best thing we ever did for him. From this we were able to get an IEP (Individualized Education Plan) where he was pulled out of the classroom for extra help with a resource teacher for a short time each day. This worked wonders for him. He is now in High School. He stills has learning disablitlies, but knows what they are and has been able to use his strengths to overcome many of his issues. He's learned many strategies and recognizes how he learns best. He's in all honors classes and makes A's and B's. He's actually a year younger than my oldest and is in some of her honor classes.
Your son may not have any of these issues, but it's best to have a face to face meeting with his teacher and get her take on the situation. We privately tested instead of having the school do it, because they had to go through many "steps and evaluations" to get to that point. I'm so glad we did it. It wasn't easy, but well worth it.