never posted anything here, there probably allready is a thread for this, so: sorry for that, but i thought it would be handy to know.
I just played a game against this guy, he flagged me for 2nd, 3rd had also flagged me, he took care of third (which flagged out quite early)and then started attacking me.
I had just asked him to put up the flag 2 turns before, was still deciding whether he just hadn't seen it yet, when 3rd flagged and he attacked me from all sides cutting me all up
just goes to show: be certain to make them put up the flag