I think you did fine too. When people ask me questions I don't wish to answer, I reply with a similar question (in this case, How long have you been working here (or doing this type of work?) You're right, it's just small talk and just about any topic will do. I wouldn't out and out lie, as if you are working at a particular job, then they might actually be interested and ask MORE questions about your work!

You could always use technical words for housekeeping or tv watching... some kind of research or engineering would do.