I get the feeling he was indicating that his music school instituted their own grading system above 8. It's not likely a nationally recognized one. Imagine if a school allowed grades like "A++" or something like that...
Yeah, I guess. It just seems odd to me. I mean, if a school in England allowed an "A**" grade, I'd be pretty confused because it would knock the rest of their system off kilter - each previous grade would be easier to get, and you wouldn't quite know how to match it against other, nationally recognised grades.
But, I guess that doesn't really apply with music grades. Just seemed a little confusing, that's all.