First, check to see if there's something rubbing inside one of the guards. That looks pretty normal though. Where you should be concerned is the teeth themselves. check the inside face of the belt and teeth for delamination and cracking of the rubber. Check the back of the belt (smooth outside face) for cracks and checking as well. A few threads coming off the outside edge of the belt shouldn't be much to worry about. If they a really hanging out there, trim them flush. Lightly singeing (sp?) them with a lighter also works to keep the fraying at bay. Hope that helps.
Cheers[smirk]