I think it might be from the Giga library selection. Giga actually has a library of native american flutes with a few articulations. That very well could be what your looking for. It almost sounds like a variation of a ney flute as well. I know East West Ra could certainly be suspect to that sample.
Those samples are from "Voices of Native America". Lots of flute phrases from many different types of flutes on that cd. Redwood flute, birch and others. Multi-samples also. I've used them myself quite a bit over the years.