Most likely you have a seal leaking. This seems to be a common problem as I just changed this seal on my '95 zx7 trackbike about two weeks ago and just noticed yesterday that the same seal just started to leak on my '94 zx9 motor.
I don't know what the technical name of the seal is I call it a clutch rod seal????, but it is the seal that the pushrod goes through. Its about $13.00 from ron ayers.
To change the seal you need to remove the front sprocket and take off the cover behind the sprocket. On the backside of this is another seal that you should just replace while you have it off, that way you don't have to go back in there twice when the second seal decides to fail. I want to say that its also $13 from ron ayers.
I highly doubt that the seal going bad has anything to do with not taking care of the bike, after all your bike is almost ten years old and gaskets and seals are going to wear out over time.
I hope this makes sense, I'm not very good at explaining to others what I mean.