As other people precisely guessed, I couldn't see your banner; besides, when you said "explain yourself" after the incident, I wrote many things in addition to "something's wrong with my game", which can be easily found in the server logs...
I spawned and it was obvious that something is seriously wrong, because game was flashing with consecutive extreme lagspikes. Yes, I tried alt+tab but it didn't work. I didn't want to leave the server because I had multiplier, so decided to wait for a while, hoping it's temporary. Then Dave came to our spawn without banner above his head and I tried to attack him during terrible lagspikes in that flashing environment just because I didn't want to be labeled as "leecher". I suprised when he didn't attack back and I thought that he might be suffering from lagspikes as well. I barely killed him and then I saw damn red lines indicating I killed a teammate *facepalm*
Dave was very angry and said "explain yourself or you will be banned for that, etc.."
It was a nightmare, lagspikes somehow were affecting public chat screen but I pushed hard and managed to write "Something is wrong with my game" and "I swear I didn't see your banner above your head".
Then I restarted the game, immediately joined the same server, the map was changed and those lagspikes and flashing environment were gone and I said "Well Dave, I restarted the game and it seems that the problem is solved, I'm sorry for that tk"
As you requested, I tried to explain this misunderstanding but it seems you didn't care even a bit