We had a similar experience with DS in grade 1. At the first report card we were urged to test him for ADHD-I. We tested and he came out gifted/LD (WISC subcategories ranged from 2%tile to 99.6%tile). Observing him in class last year I can see why the teacher jumped to that conclusion as well as why he his grades were horrible. He simply didn't do most of what they were grading him on.

That said, the comments being good bodes well IMHO and it could just be a picky teacher/grading scale. In our case the comments were almost all negative (sometimes comically so since I knew he was capable of so much more at home but they had no idea). Good luck!