Fuel leak

I have a 1988 Chevrolet Beretta:
V6, Manual Transmission, 150k miles on it.

I have had the car sitting in my driveway for about 2 years, not running. I recently made a few repairs to get it back up to operating condition. I replaced the water pump, the fuel pump, and a battery. Everything runs and sounds great. Except for the fact that there is a small gasoline leak comming from the schrader valve on the fuel rail assembly. Anyone know what may cause this or how to fix it?