Wow that is kinda weird. But i've never seen anything like that on the xbox, so it must be a PS3 thing.
I know on the xbox, occasionally, once in a great while a player will show up as 'blue' on the radar (sorta like what R-BADD7 was saying). The blue player isn't on either team and if you shoot it down it doesn't count. But they can still shoot you down.
Strange stuff, but makes it interesting every now and then
