Really? That's strange. First I've heard of them doing it not related to breeding. Anyone else see it when not being bred or with another ball python of opposite sex around?? I know corn snakes and other species do a tail "rattling" to warn someone off, but never heard of that happening with a ball python. Only hissing.
That would be my main guess, but I suppose I'm -mainly- curious as to if it's a "I'm ready" sign or a "Get off me!" sign. Lol.