Maybe its connected to our genetic past where graying hair (or fur) meant weakness or . . . dinner, not sure, but nowadays looking older seems to bring about a shift in perception and thus response.
If I hold a door open to someone (which I do often) I sometimes get a thank you tinged with a bit of - so happy you are still able to do that. Not snarky at all - just an acknowledgement to the effort involved.
Do I like that - not really, have to admit. I do it because its good manners and it feels right.
I think compliments like you mentioned are frequent woman to woman gestures. I never get one by another guy for my new pair of Merrell slip-ons. It just isn't done. We're more into a nod or a swift lift of the chin in acknowledgement and it suffices.
I'm not sure a compliment in return for a compliment is a sign of rejection - more like a - gosh so happy I got one maybe I should give one back. Awkward I admit.
Funny piece. Thanks for it.