Problem with kegerator

So I picked up an Avanti 40BRC/RW/RB mini fridge. I had to bend down the freezer tray to fit a keg in. I set it at the lowest (warmest) setting and put in a corny and left it. After a couple days I checked on it and the beer froze up. The keg is touching the freezer tray but could that have done it? Im debating picking up a johnson controller - could that solve the problem or should I try something else?
thanks!