There is a possibility that he could not see the banner over your head due to a glitch. However, I find it hard to believe that he would completely disregard the namebox that shows up when you face a teammate and the teamwound report message in the middle of those five hits depicted against you. On top of which it does not seem as though you were defending yourself in any way, which should have also indicated to him that something was wrong. I have to conclude that this was intentional.
24 hour ban for teamkilling.
