if you are using a theme other than the default one, you may want to try the default theme to see if the mood will change? (dropdown box to change theme is bottom left on the main page http://neurotalk.psychcentral.com/index.php )

I can't think of anything else it could be other than the unread private and/or profile messages or an incoming friend request that I mentioned before

I checked your account and all seems in order with your current mood showing there too.