Betraying teammates without ever attacking them?

Hello, I was playing a game of Halo 3 infection on Narrows recently when the game claimed that I had betrayed someone shortly after the game started, but I never attacked any human teammates. The same person then proceeded to get “betrayed” by me two more times which ultimately led to me getting kicked for no reason. When I looked at this person in Theatre mode, it looked like he just brushed past me and then jumped off the map, even though I didn’t shoot or melee him at all that game. What is going on here?