If it sits for long periods between rides the clutch will stick, I had a Tri-z way back that sat for a while, I fired it up and had to rip it on the road with the clutch in to break it loose. this was a extreme case. I usally hear this from bikes stored in hot climates and not run for long periods. 

That could be the problem, I mean it hasn't been rode much in who knows how long so.