Yeah, I had this bloody problem right before I had to have my bike tore down for a torsional damper bearing problem. BUT don't worry! It could be nothing more than a weak clutch cable or worn clutch parts.
What is your mileage, mods and how often do you use the clutch (lots for city, not much for highway)?
You might have made the bracket holding the clutch cable up the engine case bend with use. Try adjusting the cable at the bracket about a half inch higher or 10mm. Readjust the cable at the hand control accordingly to compensate. This keep the cable tighter without going to the limits of adjustment at the hand lever. You can also try moving the clutch arm back one notch for same effect.
If you can't get proper clutch adjustment that way then the next place I'd look is inside the clutch. Your thrush washer, bearings or something could be overly worn.
You may also have a bad clutch cable but they don't go bad often. I'd look more at the other clutch components and replace the cable if there isn't anything else wrong.
If the bike is under warranty be sure to have the dealer troubleshoot. They may determine you need more work than clutch stuff.
