Carpets are not venomous. That said, many/most snakes have some proteins in their saliva that resemble venom precursors and can have a degree of biological activity.
Something I would ask though - had the animal recently eaten? Being as I suffer from an extreme allergy to rodents, I know from experience that catching a bite from an animal that has recently eaten a mouse/rat can lead to a gnarly anaphylactic reaction that an uninformed doctor might decide is envenomation