for sewing to come undone or for something to crack or split (see Molina)
Alonso de Molina:
ciotomi. (pret. ocioton.) descoserse la costura, o resquebrajarse alguna cosa. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 22v. col. 1. Thanks to Joe Campbell for providing the transcription.