Ditto on it bein random hit/miss.

Going into the UK at Gatwick a friend and me were traveling together and there was a school group of teens ahead of us.. like nearly preteens. They explicitly split the kids up into singles - there was a barker.

Then when it came my turn, i went up, got asked where i was going and with who etc.. and the girl says "Why aren't you together then?" as my friend was at the next counter. He was giving the identicle info about who/what and she heard it and said "next time, stick together."

Coming back into EWR, they were doing it by "group".