I read Sally McCabe's article on getting the garlic bulbs in the ground (in the Philadelphia Inquirer around October 6-12th).
You planted garlic bulbs on the surface this fall and they have sprouted. They may survive the winter, but I doubt that you will get a very good crop. Cover them up with at least an inch of soil on the bulbs and the put some crushed leaves over the bed. Fertilize them well if they show signs of growth in late winter.