Why would my dad react this way?

I was in the kitchen getting some coffee and he came in too, I smiled at him, and he immediately snapped at me "what are you smiling for?"

I didn't really how to respond so I kind of just chuckled awkwardly and said "I don't know, just good to see you I guess" and then he told me that was weird. I hurried the heck out of there after that.

I'm autistic so I don't process emotions or facial expressions well, kind of just left me confused. Is it weird to smile at people like that?