I don't generally ask those kinds of questions. Mine are more of the algorithmic variety (i.e., given this problem, how do you solve it?). Having said that, the last 10% of getting the job is demonstrating that you know SOME programming. I may ask you some programming questions like the one you presented, just to see whether you know programming at all. If you got this right, you're 95% of the way in the door, as opposed to just 90% of the way in the door. It's not a deal breaker -- I can teach you the difference between 4 and '4' -- but it's a huge plus if you get it right.

Plus, like the article says, most people suck at tech screens, so that interviewer may have just been asking random questions with no clear idea of what they're looking for.