Elena wasn't low-class, but she didn't know his name. Now if she said 'boy' than that could be interpreted as low-class. She was one of those Canadians, although living in New York had made her less friendly and less passive. If anything, she was one of those people who had became more of a New Yorker.
'Or you could ignore it and move on. Like I intend to do,' she spat and turned to go.