Puppy owners get this all the time
While it's certainly flattering for strangers to want to love on your puppy, it can get pretty irritating, fast. I know there are many people on here who have had "those" type of stories/encounters with random strangers approaching their dogs in a way they don't really care for. One time when I was at the bank and brought Mocha with me, the teller was like "Let me see him". I brought him closer so that she could pet him, but to my surprise, she actually leaned over the counter and grabbed him from my arms
I started backing away when she did this, hoping she would get the idea...but she still went for it rather insistently
Some people think that if somebody takes a dog out in public, that it's fair game to play and interact with them. They just don't understand that we see our furbabies as parents see their skinbabies.