This sounds like normal cold clutch drag to me. Mine has done it since new and still does it now, albeit to a lesser extent, after 130hrs use. Every bike I've ever owned with a wet clutch, including many road bikes, have suffered increased clutch drag when cold. Two things can help.
1. Before cold starting 'break' the stiction between the clutch plates by engaging 1st or 2nd, pulling in the clutch and pushing the bike forwards a few feet. This is easier if you are pointing downhill and you can just sit on it and your weight will help stop the rear tyre skidding. This is what I do as the drive from the house is quite steep.
2. Let the bike warm up for a few minutes to thin the oil. I never ride off until the temp gauge reads at least 60 deg C. I use 15/50 oil. I tried 10/40 but this made no noticeable difference to the cold clutch drag.
