I'd get it winterized ASAP. The fact it is a '4 season' rig really does not mean much. Utility bays have marginal insulation (doors are thin and the bay itself is usually blow-molded plastic) and '4 season' assumes you will be in it with the heat on. This keeps things like the utility bays from freezing by means of heat ducted into them. If the camper is sitting unattended with the heat off, true, the living quarters will hold heat for some time from the better insulation but without the furnace running, the utility bays will track the outside temperature pretty close. Trying to replace broken fittings back in the undersides is no fun. Your hose being attached with the camper unattended is another no-no. If it was in the 20's, it's very likely it has frozen. You'll be lucky if the outside hose connection has not been damaged. Even an occupied camper would need the water running at a trickle to prevent freezing or better yet, a heated hose.
