From your description I would suggest these people could possibly have a serious problem. If the dog was barking at you and then lunged and bit you to me that is not acceptable for a young puppy. Sounds like possible fear aggression or at least a less than sound temperament.
I certainly do not not tolerate biting from my puppies and would be seriously concerned if one of them was barking crazily and then lunged and grabbed a stranger. My puppies dont get a lot of socialisation because of where I live and they are all high drive and still they would never behaved like that in public. It would be a massive red flag.
Indeed I have once owned a dog with genetic fear aggression towards strangers and it really started to surface around that age and I had to work very hard to train and manage her.
Tetanus shots are reccommended every 10 years, so if it is longer than 10 years then a shot is wise. A dog bite can turn nasty - a friend of mine had one turn septic and she was rushed to hospital with scepticeamia so watch out for any sign of infection.