It has been suggested to me that a sticky residue builds up on the clutch plates and makes them stick together, which makes it hard to change gear. The fix for this would be stripping the clutch plates down and cleaning them if new or replacing if old. However, I am not sure that this the actual cause.
I still think that it is a combination of heat expansion and cable adjustment, as mentioned by Sid.
As for the oil cooler, my Pointy has one as standard and it still does it. Mind you, it does sit right behind the exhaust, so gets the heat from there! Silly Suzuki... Nice to have it though.
