Hypothetical, of course

Imagine someone tells you about a certain experience. Something that freaked them out, something they thought you might be able to relate to. They describe the atmosphere and practically put you in the scene. It sounds like it must have been extreme, but can't 100 percent relate to the certain situation. Just the next night, in an eerie state you begin to feel the familiar sensation of de ja vu. The same thing happens to you, and you can then completely relate to that person. Feeling guilty about not understanding before, you wonder, is too late to change that? Or at the very least to discover something new? Probably lost you on that last part.. but that might only be comprehendible to me.