Yes, I've had this experience, and my DD10 used to be like a magnet for identifying gifted kids. I don't know how she did it, because she is on the spectrum and generally crummy at noticing much about other people. But in any given environment, she somehow ends up buddying up with the most gifted kids around. (For example her boy best friend who she met on the first day of K--turns out to test HG+ also a couple years later. Which in hindsight sort of explains a lot about my interaction with her teachers that year.)
I think it has to do with intimate familiarity with a gifted child (and likely other gifted children in the family, or close friends). Teachers do not get this sort of ever day on-the-ground experience.
