I have POTS but I'm not dying

I was at a restaurant and I was salting all my food and some lady came up to me out of nowhere and said"you know that much salt is bad for you" I explained to her I salt my food a large amount because I have POTS she then In a sympathetic way said"in so sorry let me pay for your meal your going through a tough time" I declined and explained that I am capable of paying for my meal she has a surprised look on her face and walked away

Why do people do this yes I am disabled but I'm not on my deathbed . I'm not offended by they're actions and I think that is good to spread awareness of POTS but why are they so sympathetic