You are probly correct. A hard plastic line runs from inside the car along the drivers side of the engine compartment and under the battery to an electric vacuum pump (pump mounted to underside of battery tray). Battery acid eats away at the plastic line (easily replaced). I like to cut the hose back by the strut tower and splice in a replacemnt hose, using rubber vacuum hose as the joint, and reroute the replacement hose over the transmission (by the lower radiator hose/wiring harness bundle) and then down to the pump, so it will hopefully last longer.
Another problem could be the plastic switch, that shuts off the cruse when you step on the brake pedal. It could either be broken or just out of adjustment. I'm not sure how famillar you are with cars or your new car, but if the vacuum hose doesn't fix it, I or some of the others on this board, will tell you how to check this.
Or, you could just take it to your local dealer and have them take care of it. This is my personal favorite, my kids need shoes......lol.
Good luck buddy.