I don't know much about brindles... is the color of his skin patterned like the hair? I'll do some research on brindle... he could grey out if it's not a "true" brindle.
I would think the breeder would want it's babies registered, and I don't see why they WOULDN'T sign your papers. Surely they'd remember their brindle baby ;)
Every great dream begins with a dreamer. Always remember, you have within you the strength, the patience, and the passion to reach for the stars to change the world. ~Harriet Tubman