Answer: I think that when a mother mocks her adult daughter's interests publicly - and invokes what is traditionally one of the sorest possible subjects for extra, public laffs - and then is shocked, shocked! when it offends, the mother sounds awfully disingenuous. And frankly kind of mean.
Unless the daughter tends to find such ribbing funny. But, she doesn't, does she?
You seem to know the route for getting under your daughter's skin. It also seems as if your daughter marks that route clearly with slightly-too-loud (and therefore slightly defensive-sounding) announcements of her fitness accomplishments.
If she had written, then I'd ask whether she doth protest too much. But since you're the one who wrote, I'll ask you: Why not just say, "Yay!" then leave her be? Whence your impulse to tweak her, that's your "strange reason" right there.
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