happens all the time.
keep them separated. i own 5 snakes and one 12-year-old cat. i thought she was safe around me when i held my snakes because she's old and just wants to cuddle. one night she felt the snake near her, quickly whipped her head around and started licking whatever was irritating her. i couldn't react anywhere near fast enough had the situation turned sour.
don't take a risk on your animal's safety.