Notifications syncing between devices?

Maybe I am missing something simple but I'm having trouble with notification center.

Let's say you get an imessage on your iphone and ipad. If you read it on the iphone, the notification goes away on the ipad since it has been read. I like this.

However, notifications dont seem to update for me like that in ML. When I open up my laptop, I get a slew of notifications for already-read imessages and the like. Is this something that happens to everyone, or am I missing something? It doesnt seem like this should be how it works.

Thanks in advance.