I'm the same way. If I'm not currently working in the specific area I'm given a question in, it can take me a few minutes to access that information in my head. And therefore, I look like I don't know the answer.
I recently was in an interview for an iPhone dev job. I was prepared to talk about Objective-C/Apple SDK since I was working with that. However, they started digging into projects I had done at my last job (in Java). I struggled. I just hadn't thought about that work for a few years, and probably came off like I was embellishing my resume. After the interview, once I caught my breath and thought about it, all the details started coming back. Needless to say I was kicking myself for not being able to recall it sooner.
I recently was in an interview for an iPhone dev job. I was prepared to talk about Objective-C/Apple SDK since I was working with that. However, they started digging into projects I had done at my last job (in Java). I struggled. I just hadn't thought about that work for a few years, and probably came off like I was embellishing my resume. After the interview, once I caught my breath and thought about it, all the details started coming back. Needless to say I was kicking myself for not being able to recall it sooner.
Just the way my mind works....