The Play Store app is somewhat special among Android apps, in that it is updated silently. Google recently updated their Play Store app to use the new drawer layout. It has been rolling out over a several-week span.
When I got it a couple of weeks ago, I realized it only because the menu went from around six items, down to just two. Fortunately, I had read that this update was coming, so I figured out pretty quickly that the other menu items had been moved to a drawer and all was well.
A few days later, my son couldn't find the 'installed apps' section. I showed him the new drawer and all was well.
More recently, my elder daughter couldn't find the 'my wishlist' section. I showed her the new drawer and all was well.
I know other cases of people encountering this little bump in the road. On Google's Android development site, there is discussion about the relatively-new drawer pattern. There is even discussion of how to introduce users to your app's drawer, so they won't be confused. Too bad the Google Play Store app developers couldn't have paid a little closer attention to Google's developer suggestions.