Thresh's lantern can creep block him?

My last game, I was playing a game with my favorite champion, Thresh . A moment came when I was chased by two opponents in the jungle on the other side of the wolf camp (Blue side of the map). I wanted to survive as long as I could so I put my lantern on me (W). All of the sudden I got blocked by my own lantern. The feeling was exactly like when you get minion blocked, but the only thing that was in front of me was my lantern. Thresh tried to go around the lantern one way, but after he changed paths to try and go around the lantern the other way. By that time, I was already caught. Was that a bug?