I would not be worried about your cat's sudden attacks !! I'm sure it just got startled and attacked in a moment of fear : his instinct tells him to do that to foreigners !!)
Sydney always attacks when my daughter Indra walkes in with her tiger-slippers on ... He thinks those are real tigers ... hahaha . He also attacks when I lay down on the couch and move my fingers ; this is the fault of my son , who learned Sydney this when he was still a small kitten .... Shame on him , I know , but it is to late now to re-teach him . But after all , Sydney is a sweetie you know !!!!!!