By embedding “dilute” gold nanoparticles in single polystyrene thin films as “markers”, we probe the local viscosity of the free surface at temperatures far above the glass transition temperature ($T_g$). The technique used was x-ray photon correlation spectroscopy with resonance-enhanced x-ray scattering. The results clearly showed the surface viscosity is about 30% lower than the rest of the film. We found that this reduction is strongly associated with chain entanglements at the free surface rather than the reduction in $T_g$.