The 1.4.0 RC update appeared after the sneaky little 2.0.1 Android GO app update on the Google Play Store, probably for the P3 model-A controller. And then it seems to have disappeared overnight. I happened to get it yesterday, but notice no changes. It was probably a very-minor change.
As far as the GO app 2.1.0, it's listed today on the DJI website as the most current for iOS devices.
Who knows? If it's flying and taking good pictures, you're probably in great shape!