Why Am I Still Mad At My Sister For This Old Thing?

So my sister, let's call her Emma, she's the oldest and she always gets away with everything. I’m the youngest, so you can imagine how annoying that is sometimes. Anyway, this happened a few years ago, but it’s been bothering me ever since. Back then, we were all home during Christmas break from college. It was supposed to be the best time of the year! But Emma had this weird habit of sneaking into people's rooms and moving their stuff around as a joke, you know? Like she’d put someone else’s pillowcase on my bed just to make me think it was them sleeping in there. Well, one day, I walked into our shared family room after Christmas dinner, and sitting right next to the TV where everyone gathers is a brand new DVD player. But here's the thing, we were all supposed to get new gadgets for ourselves as gifts from under the tree that morning. This was clearly not mine. I immediately thought of Emma's pranks and went straight to her room, but she wasn't there, so I asked around. And then someone pointed out they saw her carrying something wrapped in a big box earlier. Light bulb moment! The whole family was freaking out because the new TV had suddenly stopped working that day. I confronted Emma about it, pointing fingers and saying it must be her since she's the prankster. But guess what? She actually bought that DVD player for our mom’s birthday as a surprise present. It wasn’t even meant to be a joke or anything. Despite all my accusations, when I found out the truth, I was more annoyed at myself than her. Here I am thinking she's causing trouble just because of her mischievous reputation. But now it feels like there’s this unresolved tension between us whenever we talk about Christmas gifts or surprises. So here’s where I need some help, is it normal for me to still feel a little upset years later, even though everyone knows the truth and she's not at fault? Should I just let go of this and move on since nothing bad actually happened because of her supposed prank? What would you do in my situation? Am I being overly dramatic?