Yea, I have never had kids... but it's my natural shape.
Somebody once asked me in the library, "Are you blessed?" Took me a few seconds (okay, he's looking where?)... and I'm afraid I replied "No, just bloated!" PMS will do that...
You have done a service, I hope - the embarrassment had to be both-sided! Take it like a woman
... oh, and it's your firmer, fitter you that is why the contrast is greater. If you were flabbier all over she wouldn't have thought or said such a thing...