The Note I Secretly Stashed in My Classmate's Backpack

So... this past week at college, there was this thing that happened. You know how sometimes you just can't help yourself and you do something you think is super smart at the time but then later realize it might not have been the best idea? Yeah... I sort of did that with one of my classmates, Alex. We've known each other for a while now in our major classes... It started out as a friendly relationship, mostly just working on projects together and helping each other understand some of the tougher concepts in math class. Anyway, a few weeks ago during an exam review session, I kind of overheard Alex talking to someone else about how they were stressing out about this upcoming test. Now... at first, my intentions were good! I wanted to help them relax and do well on it. I even wrote up some notes with all the key points from our past classes that could be relevant for the exam. The problem is... instead of just sending Alex a copy via email or handing it to them face-to-face before class, I thought it would be funny (or helpful?) to secretly put my notes in their backpack when they weren't looking. It seemed like such a clever idea at the time! But then as soon as I did it... I got this sinking feeling deep down inside. What if Alex finds out and thinks it's weird or intrusive? Like, what was I even trying to accomplish with that move anyway? And now here we are: test day is over, and while I haven't talked to them about it yet (mainly because I don't know how), but I've been replaying the whole scenario in my head since then. Am I just being overly paranoid... or was this a real mistake? Can you guys give me some advice on what to do now? What should I say to Alex when we finally talk about it? Should I apologize and hope for forgiveness, or try to make light of the situation and move forward as if nothing happened? Any thoughts would be appreciated... thanks!