My wife and I just adopted Mannie 2 weeks ago. He's an approximately 2 1/2 month old male orange tiger. He continually attacks Midnight, our 3 year old female tortie. She will swipe back at him, but it usually ends with her hissing or growling and running away from him. We've allowed them to be together for about a week now, under supervision. As this past week has progressed, Mannie's gotten more persistent. Is this just playfulness on his part? Should I be concerned?