According to wii fit, I am at risk of being overweight?

How is this possible if when I flex I can see a four pack? Don't you have to have a generally low body fat to see abs? Do I just have a lot of muscle weight? It said My bmi was 23 point something. I dont understand, I dont want to be overweight. I also have pretty big arm muscles and I can easily flex my left pec, not my right as much. So do you think I'm just muscular? If I was over weight I wouldn't be able to do 10 pullups. Is wii fit just inaccurate?