Bob is walking with a friend, Inhae. They are discussing cars. Inhae says she would like a Tesla. They laugh because neither of them can afford a Tesla. Bob says he is buying a new Toyota Yaris and he might sell his 2010 Mazda Demio for $100,000. They laugh again as a 2010 Mazda Demio would only be worth about $5000. Inhae asks Bob what he would sell the Mazda for. Bob says he might ask $6000 for the Mazda. Inhae says that's a bit too much for her. Bob shrugs. They walk further. The next day Inhae phones Bob and says she has decided to accept his offer to sell the Mazda to her for $6000. She can give him the money now so he can put it towards his new car, and she will take delivery of his old car when the new one arrives. Bob is confused. He asks you for advice.

Explain to Bob the legal significance of his conversation the day before. Does he have to sell the car to Inhae? Base your reasoned answer on cases we have studied.