The deal is just that you're getting older. Your ears just don't work as well as a 12year old's. Neither do anybody else's your age (within the bounds of typical human variation - probably well over 95% of use _never_ heard 22kHz, not matter _how_ "young" our ears were).
I was once in a small, treated room working with some rather large PA speakers. I was curious how far my hearing range actually extended, and did something very unwise: I played a 20kHz tone and very briefly ramped the volume up and down. I definitely heard it, but I also induced quite a lot of pain. I learned two lessons: 1. my threshold of hearing at 20kHz is near or above the threshold of pain, and 2. don't do that ever again.
heh, your story reminded me of the bar scene in Good Will Hunting:
WILL: The sad thing is, in about 50 years you might start doin' some thinkin' on your own and by then you'll realize there are only two certainties in life.
CLARK: Yeah? What're those?
WILL: One, don't do that. Two -- you dropped a hundred and fifty grand on an education you coulda' picked up for a dollar fifty in late charges at the Public Library.
Yeah I get that I'm getting older. It's just, what's the point of having a stereo that gives perfect playback at 22 kHz if you can't hear it? I'm guessing there must be something since people buy gear like that, or is just a case of deranged audiophiles?
You might not hear a pure 22kHz sine but any sound from, say, a harpsichord will have much off these highs, and some think it is a part off the sound, that one feel without actually hearing it. I'm not endorsing this view, sound islike wine tasting, a lot of hand waving and few solid ground.