Sometimes you choose a metaphor, and you end up stuck with it.
Well, as short-term memory gets worse as we get older (completely normal) we started "joking" around that sometimes you can't "think" yourself into remembering. You have to submit a "call slip" to the Librarian, and you can't keep her hung up at the desk saying "Well, do you have it yet?? Do you have it yet??" — you have to give her time to go "downstairs" into the call room to retrieve the information for you.
Well, some things aren't in our File Cabinet and we can't find them. Misfiled, put into deep storage, etc. and we've lost the link to it.
So our "Librarian" is an interface that's relatively new. We submit the "call slip" (a request) and if we get on with life, she often fetches the information — sometimes in moments, minutes or occasionally hours — and passes it back to us later.
Yes, this is typically a normal mechanism. However it's also a "fragment" represented in the internal landscape. Our fault for making it a metaphor. The internal landscape is nothing if a mental metaphor.