After you just stared at her in bewilderment, did her facial expression show that she realized she was out of line to comment on that to a stranger? Or did she not get the point?
I had a somewhat different reaction to the same scenario.
I've been walking with a limp for about 18 months now. Some days are worse than others. My podiatrist and I have been treating plantar fasciitis in both of my heels with no success. Next weekend, I'm getting an MRI on both heels to see what is really going on. My point in giving you my history is that allegedly what I have is common. And allegedly, it's treatable and my limp should not be permanent. So, in my mind, I don't think of myself as "someone with a limp." I also have a significantly worse health issue, totally unrelated and so I'm always focused on that, and not on the challenges that my limp and heels present to me.
A year ago, DH had to have a significant surgery on his heel and he was on crutches and in a cast for a long time afterwards. We were at a friend's wedding. I had to wear dress shoes, so that was exacerbating my walking pain. But after the surgery that DH had just had, I didn't want to focus any attention on my pain, or anyone to focus on me since I was trying so hard to be the steady, healthy spouse in charge of the children, while DH was resting his foot and doing his best to just even attend the wedding.
We were at the reception and another guest made a comment to me about my significant limp. I had been focusing so much on appearing to be the spouse with healthy feet that my immediate reaction was "I don't have a limp!" And the lady said "It looked like you were limping around." I just said "no."
And then I paid attention the rest of the night, and the rest of the month even, and she was right. I limped 100% of the time. I hadn't realized that.
Normally, I would never refute something with gaslighting or denial. But it was really effective. It shut her down pretty quickly. I might try that tactic again in the future. Or complete silence. Those are good responses.