I've had exactly the same thing myself. I initially put it down to when i did my first bleed of the clutch system. I thought it dropped because some excess air may have been trapped and had now left the system. I topped it up but its still continuing to drop slowly.
As with yourself, there are now obvious fluid leaks and mine seems to run fine.
All i can assume the reasonng behind it is:
a) clutch plates are excessivley wearing
b) hoses are worn
Looking to P/X mine for a Aprilia Tuono in a couple of weeks so it'll be someone elses problem then :wink: .