Even though I have comment moderation turned on, I get a notice at my email every time a comment is left, which is why I'm usually able to approve them relatively quickly. Once in a while, though, I notice that some comments come along that do not get sent to me by email, so the only way I know they're there is to see them next time I log into Blogger. There's been a small uptick in this sort of thing over the last week, so if you notice your comments are languishing longer than usual, that's why.
Now, if you'll excuse me, I gotta start Christmas shopping. (Yes. I said "start". Oy!)