Moments like this will become more and more frequent as you level up. Even though I’m nearly level 60 I still get excited when I see something in the wild that I’ve just studied. It feels so rewarding and lets you know that you are actually making progress.
One of my mind-blown items was the 左右 (さゆう). In kendo we have lot of funny terms which most of them you just learn to say and what they mean, but I doubt most people actually look into the origins of the saying. So every warmup we do sa-yuu-men, which is repeated left and right strikes to men (head). So when I saw the kanji for left and right, I got that lightbulb moment of figuring out that it literally means left and right when we do sa-yuu-men.