Why do I lose the ability to edit some posts before the 2-hour mark?

I just noticed something strange happen. A few minutes after I posted a comment, it got marked as "[flagged]". At that point, I couldn't see it in incognito windows, but I could still edit and delete it. So far everything made sense. A few minutes after that, "[flagged]" went away and I could see it in incognito windows again, but now I can't edit or delete it anymore, even though I'm still well within the 2-hour window. What happened here?