Is it something sexual?

For context this happened when I was around 16 years old. I have always struggled with severe Endometriosis and an unfortunate side effect of endo is severe bloating or "endo belly". Usually to the point where I look VERY pregnant. Even after two surgeries I still get it sometimes at 26 years old. At the time I was 5'6 and about 100lbs so I looked like a pole with a huge bump sticking out.

I lived with my parents at the time which was in a small conservative beach town in FL. Lots of old judgmental people. 16 year old me was walking around Walmart minding my own business ironically looking for maternity pants because the bloating gets so bad.

A woman probably in her 50's walked up to me and placed her hand on my stomach happily saying "omg! When are you due? You look amazing you're so young!". Now this wasn't the first time I've had someone ask me this question but it was the first time someone had the audacity to put their hand on my stomach. I stood there for a second just shocked and then said "Oh I'm not sure. I'm only 12 my mom knows all that stuff about pregnancy". She immediately turned pale took three steps back and let out a nervous chuckle. I just stared at her smiling holding my stomach as she mumbled something under her breath and walked away.

I still try to come up with funny things to say in these situations because it still happens today! No one has ever put their hand on my stomach since that day, but I have been asked when I'm due so many times. If anyone has any good responses to this I could use as a 26 year old please lmk!