While reviewing first posts, I just came across a post which I have previously commented (not during the review process, that is). Surprisingly enough, the "I'm done" button was already active for me at the review page even though I haven't done anything yet:
I'm guessing every action done with the post before reviewing it will count for this, which leads me to two points:
- If it's the way it should work, that means the system thinks I've already taken some kind of action about this particular post, hence it should not be in my review queue at all.
- If it's a bug, the button should obviously be grayed out until I do something on the review page.