A group of plaintiffs alleged that a gas station ran a promotion with an advertisement stating that if individuals purchased ten gallons of gas, they would get a free ski lift ticket voucher upon presentation of their gas receipt. However, when individuals attempted to obtain their ski lift ticket vouchers, the gas station gave them a "buy one get one free" coupon that required them to purchase one lift ticket at full price from the ski lodge in order to get a free ski lift ticket. The individuals who purchased ten gallons of gas alleged that a contract existed between the gas station and themselves because the gas station's advertisement was an offer that they had accepted. Were they correct? Why or not?