I hadn't noticed this problem until I read this thread but I can reproduce quite easily. Phone is in Portrait throughout.
- Slide or press top left button to expose Groups browser.
- Select a subset of books e.g. click on my tag called 'Crime'. The text Tags:Crime is displayed next to top left button.
- If I slide-close the browser to return to cover view then the Tags:Crime text remains in-situ. However, if I click the top left button to close the browser (instead of sliding), the text disappears.
Android 4.0.4 BTW