Followed at the grocery store

I was doing some grocery shopping after work when an elder gentleman casually remarked, "Blue tastes disgusting." As I couldn't quite hear him clearly the first time, I asked him again what he had said. He pointed toward my re-usable grocery tote and mentioned the "blue Gatorade flavor tastes disgusting." Strange. I was taken aback. My Gatorade bottles were buried in my tote and clearly not visible so I reasoned he must have been watching me shopping in the beverages aisle on the complete other side of the store, probably some 5-15 minutes ago. It seemed that he had to get the last word in as he approached me from the side two more times shortly after, mentioning all Asians still had their masks on, his opinion on the best flavors, and rising bottle prices due to inflation problems. I decided engaging wasn't worth the trouble and just said, "Thank you!" and smiled both times he re-approached. I wanted to finish shopping as soon as possible. I felt uncomfortable. Like I was being watched the rest of the grocery trip.