I would check the belt teeth closely for missing teeth, cracks, or splits. If you see any of these defects then you should plan on replacing the belt. Fortunately, it is not very expensive, compared with any other motorcycle drive belt. I think you will find that the cost is around $80 retail. In any case, you can tighten the belt and keep riding if you wish. The worst that can happen is that some of the belt's teeth will sheer off resulting in lots of "ratcheting" and possibly leaving you stranded. If you have a way of getting your bike back home or to a shop (such as a roadside assistance plan), then you can chance riding your bike while a new belt is being ordered.
Installing a new belt should not be too much trouble. The rear wheel comes off easily. The motor must also be moved enough to get the new belt back on the front cogwheel, which means loosening the motor mounts and/or removing the swing arm nut (watch out for the set screw on the nut) to obtain clearance between the cogwheel and the swing arm pivot.