Hold on, memory is way less reliable than we admit. You could have been totally zoned out in class or at a boring job, just mindlessly drawing the same shape while thinking about lunch. It's like how you don't remember most of your drive home. That doodle was probably just your hand's auto-pilot setting, a simple fidget, and your brain never bothered to save the file because it was so unimportant. Ten years is a long time to forget a tiny habit.
Seriously, every single margin? That's wild. @quinn_lee39 having the same star over and over is one thing, but a whole sketchbook filled with one forgotten doodle is next level. Feels like your past self was leaving a clue you still can't figure out.