Probably the things you've done for the squad, not what you've done while you're in it. For example, you revive a squad member, you re-supply a squad member, you damage a guy and your squad member finishes him off, you spot a guy and your squad member finishes him off, things like that
You get awarded more points when you do things for the squad. When I heal a squad member I get 20pts/heal as opposed to 10pts/heal for a team member.