An odd thing has happened today: somehow I've gained +20 reputation (from 519 to 539), yet I don't see what this increase is for. As you can see on the attached screenshot, the last two reputation changes do sum up to +20, but they happened one and two days ago, not today.
I didn't answer any questions, just left a couple of comments. I've also signed in in meta, which added +100 (also not displayed in the history, by the way), but that was only after I saw the discrepancy with +20.
Is it a bug in history reporting, or maybe I'm missing something?