Its called gas line freeze. Used to be a big concern 30 years ago but with the alcohol in the gas now, not as much. Use a bottle of Heet de-icer in the tank once in a while in the winter to clear the water out if you are susceptible to it.
You may have gotten some water with the gas but I suspect you may not keep your tank as full as you should. When you let your gas tank get down below 1/2 tank, there is air in the tank. When the air cools, it cannot hold as much water as warmer air, and water droplets condense inside the tank. Keeping your tank at least 1/2 full or more reduces the change of water condensing in your tank.