It's is part of their 10b5-1 compensation plans. The amounts and dates of future transactions are set in advance (in this company's case, that was early 2012). Once the schedule is set there is usually no contact between the participant of the PDP plan and the broker so as to avoid assumption of insider trading. Any officer in a company has the right to suspend a plan, however that leaves them vulnerable to insider trading investigation/litigation.
Had the plan been set up last month, I would be apprehensive, however that is not the case here.