Some strange situation.

Hi.
I have a big problem. Im normal, newbie gammer, with ratio maybe 1.1? Today, when I playing Crossfire (10:20?) Polish time, in map "Cargo Ship-escape" In UK4-1-.. room, In one round of game nobody can saw me, i was like a ghost. I dont installed any hacking software. I dont know how it done, but it was in one round. I havent screens or video, but I want know: What was a reason?
waiting for answer
"elStomatolog"

ps. One more time: I dont installed hacking software, I dont have any, so please dont reply me with this Idea.