Yep, male flowers.
Best to sacrifice one plant to protect the other 11.
For some pictures of both male flowers and hermaphrodite flowers, go to my diary "cannabis conundrums" and in week 7 you will find those pictures, as well as some other interesting pictures of some of the weird and wonderful things cannabis plants are capable of growing. The pictures may also help you to positively, 100%, identify what is going on with your plant.
Hope this helps,.........
Organoman.