Asperger's in a 5 year old?

As I have discovered that I more than likely have Asperger's (still awaiting official diagnosis), I have done a lot of research, and I think my nephew may have it as well. He just turned 5 years old. He is showing a lot of sign of autism in general - clumsiness (this kid can literally just be standing there, and he'll tip over), repetitive behaviors, physical anger outbursts (he hits his head on the floor/wall/anything HARD when he's mad or frustrated), and "tuning out" everyone when he's concentrating on something he likes. But he's not a typical autistic boy; he's smart. He didn't have any delay in language, though he did have a hard time learnng to walk. He has always loved using big words (I taught him "biotechnology" before he was 3 ;)), and he knew all his letters, shapes, and colors very early. He told me the other day that he doesn't like his frisbee to be the shape of a hexagon, and wants it to be a circle again. He then told me that a hexagon has 6 sides, pentagon has 5