Or, he doesn't know you at all, and he's just using sarcastic dry humour.
I've personally greeted people like this before, on Blockland and in real life.
It's not meant to cause offence. It can just be having a joke.
"Hi guys"
"Oh noooo, not Jim... How're you?"
Don't let people get under your skin.
People can dislike you, and they're allowed to.
They may also just be making a joke that gets lost in translation.
Take a breath and carry on. If they've not done anything more to antagonise you, chances are you've got the wrong end of the stick or are overreacting.