Why rush off to the dealer just yet?
So far you have added that it happens at slow speed, more when hot, and trying to go large gear jumps.
There can only be a few things causing it.
1, warped clutch plates, as they heat up they can get worse.
Is the cable adjusted properly? How much free play do you have in it? If it is right, try takeing more free play out and see if it is better.
Is the clutch handle bent? New bigger grips? Both of these can reduce the clutch travel.
If there is not enough (none) free play it can slipp the clutch just a little and heat it up also.
2, dry cable or loose cable housing stop. Both have the same reaction of shorting the cable draw. Dry shifter pivots can also add drag to the shifter.
3, Bent dog on the trans or worn parts. Unless you beat the bike, and shift it with out a clutch a lot at the wrong speeds these are highly unlikley.
4, You are not properly shifting the bike. Unlikley since you care enough to worry when it is not right.
No reason to give up just yet. Any problem can be fixed on a bike. And you are going to check it out better than any 10 min ride a dealer tec is going to give it under warranty.
Make sure the lever is straight, the grips are not binding up the pull length, check and re check the proper clutch cable free play, both hot and cold, and lube all the shifter and clutch pivots with a good spray or drop type lube.
Dan