It may be stretched, but either way it's not gonna hurt to replace the cable. You may be surprised at how much easier you clutch pull is also. Their cheap enough to be replaced once a year or so and keep your old one as a spare, they should be flushed with a cleaner and re-lubed often also.
If you adjust your clutch going by the case arrow/actuator arm you may need more adjustment. The arrows basically don't mean shit, sometimes if you adjust it to where your actuator is more to the right side of the case arrow it seems like you get more "throw". Another thing is if your clutch lever/perch are not right you wont get enough throw also, such as if you are running a lever with too much bend to it, it's gonna hit the handle bar before it should if that makes any sense.