I had a similar problem. My bike would leak a drop or two on the garage floor after each ride. Turns out the front sprocket seal was leaking and the oil would run down under the crankcase and drip off the oil filter (lowest point). I had to remove the sprocket cover and clean the area around the srocket then ride a few miles to confirm where the oil was coming from. My dealer fixed it under warranty. He says it is a fairly common problem and Triumph has improved the replacement oil seal.
