I've noticed this happen a few times already. This is on OS X Mavericks, btw. I'm reading something online or whatever and I get a notification that there's a new article on MacRumors. For example, about 3 minutes ago I got the one for 'Knock' iOS App. After I was done reading I went to macrumors.com and the story wasn't there. I went back to Notification Center to click the notification and was taken to the article. Again, went back to iOS Blog and nothing, even refreshed. Now it's there. Is there something wrong on my end or is there a bit of lag between when we get the notification and the article is posted? Love the feature by the way. There's lots of potential with this. Right now this is the only site I'm using it with though.