I have upvoted quit a few threads while browsing. On a few rare occasions, I’ll find a thread that I knew I had upvoted but says I didn’t. When I click upvote, the count actually changes so I know it isn’t an issue with displaying the lit up icon. It’s just a weird occurrence that I noticed happening. I wondered if anyone else had seen similar phenomena.

Or maybe I’m just an idiot upvoting duplicate threads, I don’t know.