I remember someone told me after the interview that he sometimes ask really hard/technical/obscure questions just to see if you'll admit that you don't know.
I thought he was so nice. It was a really laid back interview, we just talked about my application, about a lot of my experiences (have some unique ones, been out of school for 3 years). He asked me some specific questions about it, but didn't ask any technical questions or anything. All in all I thought it was a really good interview... but I hope the lack of technical questions is a good sign and not a bad one!