Guild Wars 2

I have swapped once because there were 3 necros (Personally I am against swapping but eh…when in roam…) . So I swapped to ranger. I believe I went from Red to Blue team because we had one necro and my name was on the other side of the board when popping it up with B.

Is this possible?

You don’t change your team when swap. It can be that someone also swapped his class from necro to X.