I tried to move, and the game automatically put me on a path straight down mid lane

Just got into my first game under the new champ select system. I was a Thresh support, and I thought all was well. After I bought my items, I tried to move, but the game put me on a straight path to the enemy base, and no matter how many times I clicked, I couldn't change direction. After I got killed by the mid laner/turret, I tried again, and it sent me on the same path to death. I managed to fix the problem by exiting the game and reloading back in, but it was a huge inconvenience and my teammates thought I was a troll. I don't know if this bug is common, but I thought I'd let everyone know.