Mike, a business representative of U.S. Outstanding Co., Ltd came to Paris for a trade negotiation and received a warm welcome. The French came to the airport to pick him up and arranged him to stay at a luxury hotel. They made Mike feel at home and he really appreciated their hospitality. When the French representatives asked him: “ Are you going back to your country by air as scheduled? We’ll arrange a car to send you to the airport”. Mike then replied directly: “I reserved my return ticket on June 15." What mistake did Mike make on the international business negotiation occasion ? ( )