-oh ,sorry I'm late.-I guess you must have been in a hurry.y

oh ,sorry I'm late。-I guess you must have been in a hurry。you are wearing your sweater inside out。第一句里,表示说话者对对方过去的假设,用过去时。第二句是现在的动作,也是对方一直持续到现在的动作,用现在时。