I once gave a lengthy deposition in a law case about an investigation that I'd worked on years earlier. Although the case was settled, the experience was an interesting illustration of the limits of memory.
The most jarring part was how much I recalled after the deposition. Various details would come to mind and I would wonder, "Why didn't you recall those before or during the deposition?"
My unspoken answer was my mind needed some time to draw things out of memory's attic and hall closet. The bad news, of course, is that had the case gone to trial, my sudden keen recollection would have been viewed as a suspicious and convenient revision. I can honestly affirm, however, that the new version involved no attempt to mislead.
That's one reason why I've encouraged clients to hold two exit interviews: one shortly before the employee leaves in order to catch anything that's hot and another a few months later, after the person has had a chance to reflect on matters.
Some events - like some people - become clearer as we move away from them.