@brandon when I interview people, I tend to start easy and go more and more technical until one of us reaches the end of our knowledge. I don't see that as a failure, but rather a gauge of where they're at technically.
Also, technical knowledge can be taught; attitude, not so much. Attitude is vastly important for me when interviewing.
What I'm trying to say is, don't worry about the technical stuff too much, as it's probably less important than you think.