Netflix has a contract with the production companies that does not allow them to release the movie until 90 days after it is shown on premium channels, such as Starz, Showtime, Cinemax, etc. Therefore, you will not be able to see these right away. Now, you would think this has everything to do with DVD sales, but only partially. DVD sales are beginning to slow as people now are switching to internet streaming, and the production companies know this, judging by their sales.
So you see the movie late. Don't worry about it. At least you saw it extremely cheaply. That's my motto.
Here's a recent article outlining a new internet streaming deal reached through the production companies, starting in September. Maybe your movie will be available only because of this:
http://www.msnbc.msn.com/id/38644039/ns/technology_and_science-tech_and_gadgets/