Welcome to the world of autism. Had the same realization a few years ago. Really cute 23 year old girl showed the same interest in me (i'm in my 40s so i didn't even consider her being interested in me). Also happened earlier in life but i was younger and too busy playing games on my computer.
Made me keep my eyes and ears more open to such signals...
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"It is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring" (Carl Sagan)