Eh I doubt that explains it. In my experience, the response is shock. Not "oh hmm well, lemme think". It's " I've never written that code since school! That's a terrible thing to ask! Why would I ever write that? "

Also, for trivial algorithms and data structures, mind blanking is a potentially bad sign. Like, if you cannot explain the idea of garbage collection (not necessarily implementation details), then I gotta question your understanding of your environment.