AITA for calling someone a silly name?

So I'm in the UK and I work in a pub and in a lot of places over here professionalism isn't really a thing in pubs. Obviously there's a standard to uphold but your regulars become friends and you can joke with them.

So I (23f) was at work today doing the lunch shift with a colleague and one of the regulars came in let's call him Ben (about in his 60s). And before he could say I anything I said "you want your usual Benny?" He said "yes. Are you trying to find new ways to piss me off?" And I chuckled and said "yeah" got payment, gave him his drink and all was right with the world. It seemed to all be in jest.

After my shift I decided I'd have something to eat and a few drinks with my bf and his friend and Ben was still there, it had been about 5 hours since our last interaction. And he just walked out the toilet as I was playing pool and I smiled and said "oh hi Benny!" As I didn't realise he was here and he stormed over to me and not shouting but quite loudy said "don't call me that. My name is Ben. I thought we had cleared this up earlier today. Do NOT call me that".

I just said okay and he walked off back over to his friend. My bfs friend came up to me and asked wtf was that about? I said I didn't know and told him about earlier but he suggested that maybe a past bully called him that name and so he hates it.

So now I'm wondering if I am TAH?