The app currently uses the library Android-PullToRefresh by Chris Banes. This library is officially discontinued for almost a year. It contains bugs that will not be fixed like this one in the Stack Exchange app: Small layout problem with refresh icon getting cut off
So my question is, why not use the modern ActionBar-PullToRefresh instead? This pattern is used by all Google apps that have refresh functionality, for example Google+, Gmail, Drive and Newsstand.
There is also an active library for this: ActionBar-PullToRefresh by Chris Banes, the same developer.