i recently took my bike to the LBS for brake service. Everything was fine until i noticed that the right lever (back brake) was leaking.
Every time i press the lever, it sort of "burps" a bit of oil and makes... funny sounds. (seen in picture 2)
I tried un-tightening the top cap, which really helped a lot but im not sure about the origin of the problem. I should note that when i took it to the LBS for bleeding, the pads were 80% worn. After i replaced them, the problem appeared (the mechanic said it's fine if you do that, but i doubt it). I should also note that i torture them a lot.