without notice, or without thinking about it beforehand, or without being warned (see Molina)
Alonso de Molina:
amo nonemachpan. no aduertiendo yo, o sin pensar enello, o sin estar aduertido. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 5v. col. 1. Thanks to Joe Campbell for providing the transcription.