Google just release a new Play Store version 4.0.27 that contain very minor tweaks and Google changed the rules of Google Play Store to put the practice of developers updating their apps through their own means rather than the official Google Play channel .
Recently some user found new version of Facebook in their devices, but it was not through the PlayStore. Instead, this update came directly through the app.
Under the “Dangerous Product’s” section of Google Play developer police, Google states that “An app downloaded from Google Play may not modify, replace or update its own APK binary code using any method other than Google Play’s update mechanism.”
It means one the application is downloaded by an Android use it cannot contact, home base and auto-update its own operating code. Instead, it has to use the official Google approved channel
Google also says that Play store is “trusted source to downloads the application and that is providing a secure experience “. While allow to application update themselves is less secure.