Last minute request

Less than an hour before the start of the mass (and half an hour before the praying of the rosary commenced), our church choir group was approached by the head of the liturgical ministry of our parish to chant the Sequence before the Alleluia as well as the Adoro te Devote after communion! We--or I should say our cantor who would primarily do the singing--were naturally distressed and upset that we weren't told well in advance so that we could learn and practice adequately. He managed to improvise a melody for the sequence and learn the Adoro Te despite no sheet music being provided but he said afterwards that never again would he acquiesce to such last minute things.