Google just pushed an update v4.1.2 to the Gmail app (up from 4.1.1 and 4.0.5) that brings a few enhancements to Android 4.0+ devices, including improved support for 7" tablets. The full changelog for this update reads as follows:
Android 4.0 (ICS) and up:
- Improved 7" support
- Bug fixes and performance improvements
At first blush there don't appear to be any visual alterations, so we'll just assume that most of these enhancements take place under the hood.
The update is live in the Store now, so you should be able to jump into the installed apps menu to pull it.