Iis it normal to find this a creepy behaviour

Last week I was at the store and a dad of a former classmate of mine (like more than 10 years ago) started following me around. He then stopped me and went "*insert name here* right?" and he got my name wrong so I just went "no" and tried to ignore him. He then said "oh I must have gotten the name wrong then, but you went to school with my son right?". He then proceeded to ask me how i'm doing and how my mother is doing. He then left. I felt extremely creeped out and sort of triggered. I got bullied during my first 10 school years which is when I went to school with his son. It was only the girls in class who bullied me but his son in particular is someone I despise. His son always had this good guy image but as the years went on his true colors started to show. He got along well with the girls and was friends with them so naturally he had a similar attitude. The worst thing he did for me is when he attacked my little brother once. My mother has also told me how his dad, this man who approached me, once squeezed her butt once. Creep!
Anyway, today I was at the store again and minding my own business. I wasnt looking around me just paying at the self checkout and when I left the self checkout-area I hear a voice and I look up and there he is standing and has clearly been standing there staring at me the entire time I have been checking out my groceries. He just goes "hey, I looked it up and your name is *insert name here*, I got it wrong the last time!" and I just went "eheh right..." Sure that might all sound friendly and normal but it certainly isnt. Ive lived in this town all my life and obviously he's seen me around tons of times over the years. Why approach me all the time now all of a sudden? It honestly makes me a bit paranoid but I might be overreacting because this is a small town and two young women my age was found dead very recently, at least one of them murdered so im on edge. It makes me paranoid when a creepy man starts to pop up whenever im at the store and following me around... Plus I still have nightmares every other night about those school years. I dont need to be reminded of that time in my life by this ugly creep. I certainly do not understand the purpose of following me around or standing and staring at me while i'm checking out at the store. He could at least stage a run-in like a normal person, like go outside and pretend to be just walking by the store when I leave. That would at least have made it less creepy than staring at me with a creep smile.