X, a shopkeeper, leaves a sealed 5 kilogram bag of a branded wheat flour at the door of Y with a note "you will like this quality wheat flour and pay Rupees 100 for this bag" without being asked to do so. Von coming back, collects the bag from his door, opens the seal of the bag, and uses a quarter of kilogram for making chapattis (unleavened bread). But next day returns the bag. Is he bound to pay for the bag? He is