It sounds to me that she is just being silly and playing, especially now that you have made it a "game" for her. My cats do it to each other all the time, especially BB. She will run up to Jasper and puff up, next comes the crazy crab walk, and then they dash off like mad cats. They never fight while doing it or make any noises other than it sounding like a herd of horses running through the house. The only thing I can see that MIGHT become a problem, is if she gets to worked up and lunges at you. If you ever see that look in her eye (most people know what I am talking about) I would end the game and let her calm down a bit. Otherwise have fun