If there is a credible concern that she may have it, and you are considering an extended period of contact with her, than there is a risk there. Depending on the research, the pertussis vaccine is between 60 and 90% effective, so at best, 1 in 10 babies who are fully immunized may still be vulnerable to catching the disease. People with the disease are contagious from the onset of cold and flu symptoms, until 3 weeks after the cough begins. Although I don't think there is any specific research about the degree of exposure you need to catch it from another person, it tends to spread within households and people who have had close contact for an extended period of time.

If I was in your position, I would consider keeping your baby away from this person. Although, if I was in your friends position, and there was a real concern I might have whooping cough, I would also be excusing myself from major social events.