Sudden Aggression

Hi All! I've had my little buddy now for almost three years. So we get along pretty well. He hops all around on me and basically uses me as his jungle gym. However, recently (the past four months) he's become aggressive toward people he's been around. Specifically my roommates. When they come in the room to sit with us he bites them! He never bites me anymore and it's shocking to see how he behaves around people. He starts moving very quickly and erratically and starts sort of running a diagonal path toward them then lashes out and bites. He hasn't broken skin yet but he's biting hard enough to shock them.

Any ideas? Have you guys seen this behavior in any of your little guys? I hate to think of him acting like this because we get along so well now!