Is Rengar broken?

I'm a pretty new player. I've been playing for a few months, and I am kinda familiar with most champions, but I'm a bronzy and it shows. This free champ rotation, Rengar was free to play. I decided to give him a try, being that he's meta and (I hear) pretty strong. I'm decently new to the jungle, I main midlaners, but I find that I'm amazingly powerful. I had a few rough games, but now I just destroy. I think I've gotten three S's in a row, my 9th 10th and 11th games. I'm mastery level three. That can't be right. As long as I don't feed, and as long as I power farm the jungle, I'll eventually snowball. Is this actually balanced? I assume I could be shutdown by higher elo players, but it seems like my fellow bronzies can't stop the Rengo Train. I'm adding a poll, but I'd love feedback in the comments as well.