Could be a leaking valve cover gasket. The valve cover gasket is responsible for sealing the valve cover to the engine and preventing oil from leaking out. Over time, the gasket can deteriorate and develop cracks or leaks, resulting in oil seepage.
Another possibility is a leaking camshaft seal. The camshaft seal is located near the alternator and is responsible for sealing the camshaft to the engine block. If the seal becomes worn or damaged, it can cause oil to leak above the alternator.