jfburk, you're on the right track - sort of. It is a requirement for a company official to file a "planned sale" in advance of actually selling. By doing this, he makes his shares liquid, meaning he can then sell them at any time, whether the stock price is up, is down, he needs emergency cash, or whatever.
While it is a requirement to sell shares, it doesn't require that you do so. Thus, company officials regularly do this purely as an insurance policy. It means absolutely nothing unless it is accompanied by an actual sale.