We're going to be having a minor update from Version 4.0.1 (Version 4.0.2 for Android) to Version 4.0.3 from 7/16, around 3:30AM (ET). It may take some time for the Google Play and App Store to reflect this. The update is to fix a few bugs.
When the update is reflected in the stores, you will have to update to the 4.0.3 to continue playing. Also, please remember to download the new version when you have a stable connection.