At RDU, the first/business/CK/EXP/PPro/Plat/Gold line can get long at times, especially late afternoon prior to the LHR flight.

The agents there have told me before that if I stand on the far side of that line, they'd call me up. Seems a bit of a DYKWIA move... would think they could solve it (if they really wanted to) with a small 'CK sign. I imagine this is only an issue a couple times a day so likely not worth the bother.