I agree with what I think Travers is saying: "spiritual", in some societies at least, has come to be a common label for something that is new and different and that the person doing the labeling doesn't have a ready explanation for. As I think Brian is implying, "magic" would have been the label in another place and time; here and now it's "spiritual", but it serves the same function.
Assuming I'm understanding things well enough, I guess I might have to make a distinction then...
My sense of spirituality is tied up in my sense of the learning process
; this is why I said those "aha" moments are essentially my spiritual experiences. When I suddenly understand some facet of something, it opens my mind to a deeper appreciation of reality, this generates a sense of awe and reverence for it. Any time I see something "unbelievable" I put it in terms of a rational universe that is simply too big for me to understand sufficiently; strictly speaking it isn't unbelievable, it's just beyond my frame of reference.
This isn't to say that something is distinctly spiritual just because it's also mysterious or otherwise unknown (The Adventures of Sherlock Holmes didn't leave me with a distinct feeling of spirituality, for example)...although I do think that sense of mystery creates a very large space for the mind to enjoy itself, so perhaps that's what attracts so many "spiritual" people to the language of other cultures...they get a little extra room to play around in the reflections of their own mind. Kotegaeshi can sound like a Great Name/Word of Power until you realize it's just "returning the wrist," so I can see how unfamiliar terms could add to this sense of mystery/magic.