pre-senior moment
a momentary lapse of thought in an individual, generally between the ages of forty to sixty-years-old or so: a brief aphasia when one cannot think of what to say or the right word for a thing, or has a momentary lapse of memory. 2. To draw a blank.
"Damn - I knew exactly what it was a minute ago, then it slipped away from me: Forgive me: I'm having a pre-senior moment."