Did Continental Airlines kill my mother?

The Associated Press is running a little article, Firms Troubled by Sick People in Office, citing a survey that shows 56% of US businesses have a problem with "presenteeism:" employees who show up for work even when they are sick. The employees are unproductive, their illnesses get worse, leading to increased healthcare costs, and they transmit their diseases to other employees.

Even worse, they transmit their diseases to the firms' customers. I try to avoid flying on Continental Airlines whenever possible, because of its Perfect Attendance Program. They trumpet it in their Annual Report. Among other incentives to come into work sick, Continental employees who have no absences are entered into a drawing for a Ford Explorer. Just what I don't want: to be sealed into an airplane with sick people. It's even worse that I might be getting my drinks and snacks from sick crew-members trying to win a car.

My mother flew Continental when she visited me in October. Four days later she had pneumonia, and died shortly after that. Did Continental kill my mother?