Thank you all for the replies. A few people i've discussed it with have said its about the pecking order. I wouldn't mind so much it just doesn't sound very nice at all. He hasnt actually bitten her or anything as far as i'm aware. Whenever he does it she just keeps running, she just thinks he's playing. We're obviously willing to leave it and see how it goes for the next week or so. I really don't think he means to be aggressive, he's such a loving dog.