Well, it's a normal game. And let me guess, the enemy team never warded properly.
Lee Sin's mechanics and mobility requires the enemy team to ward properly (or, you know, every single jungler worth his salt). And considering that Fiddlesticks has sightstone as his third item, he probably didn't ward in the first five minutes so you easily got those kills (in comparison to sightstone supports, not insulting your ability).
Is Lee Sin OP? I... don't think he is, but he crowds out weaker junglers in comparison. From the looks of this, it really looks like the enemy team was stupid in the beginning and you capitalized on their mistakes, which is what you're supposed to do. So good job.