Probably not. Motorcycle helmets are designed for use in one crash and one crash only. But they can generally withstand the force of the impact of a short drop to the floor, especially if they are certified by the Snell Foundation or by the U.S. Department of Transportation.
The real damage is done to the insulation material in a helmet when a head is inside the helmet and struck against another object, compressing the material from both sides. Once this is done, you should replace your helmet immediately, as the foam-like substance that protects your head is irreparably damaged.
For more information on motorcycle helmet safety, please see our articles in the motorcycle accident section.