I reckon it ' s either an error or that Grindy was already disguised as Graves and just did a quick trip to Europe somehow . I know they can ' t apparate between continents or even do lots of little apparitions with the Atlantic being to big , but he could ' ve had people in both Europe and NY helping him with illegal portkeys or something . Also , the time difference between the US and Europe means if this is the case he a few more extra hours between night in wherever he was in Europe and morning in NY . And if portkeys can ' t go a big distance then I guess he could ' ve portkeyed from the UK to Iceland to Greenland to Canada to America maybe . I just get the impression that he was disguised as Graves for longer than that like a few months . If not , I guess Graves was already working with Credence , because there was definitely an already established relationship there .