Are you sure?
I know NOTHING about sex determination in snakes, or if its common across all snake species.
The komodo dragon (also able to reproduce via parthenogenesis) uses the ZW system, reversed from the XY system, where the female is ZW and the male is ZZ. This lets komodo females reproducing via parthenogenesis have both male and female offspring.
Does anyone know about snakes?
edit: my girlfriend (who usually knows these things) says that all snakes use the ZW system, so the snakes could be either male or female.