I'm sure she meant it as a compliment, although I do find it a little weird when strangers comment on one's body. Somehow it feels....violating. But she probably just wanted to compliment your athletic bod! And was consequently impressed that you didn't even have to try
When I tried out a new tailor a few years ago, she openly expressed her frustration with my body type: "You are so big up here ::puts hands on either side of my chest:: and skinny down here ::puts hands on either side of my waist::." Um yes, that's why I'm coming to you.
She then told me that she could not do the job I wanted her to do (put darts in a shirt) because I was just *that* disproportionate. See why I never go to tailors?