Oil exit Moto Guzzi T3 1982

Greetings. Since the beginning of May this year I own a Guzzi T3 from 1982, with about 65,000 km on the speedometer. Yesterday I was on my way home, at speed about 120, when the engine suddenly lost power very briefly – as if the fuel was all. Was only a second long. I am immediately off the gas, but the machine then went on quite normally, no noticeable power loss, standing gas normal, no eye-catching exhaust gases or noises. I was almost at home anyway, and the last Met He behaved the Guzzi as usual. However, at the parking a small oil pool formed under the vehicle. The area under the air filter, so above the transmission was full of oil. Did the Guzzi first stop, because I could not see where the oil came out without taking off the tank and the seat. I will do that today. Does anyone have an idea where the oil can leak out?