Minor change, but I wanted to post to explain this.
This is not just a cosmetic change - some touch screen device users complained that the small buttons were not useable as they were, so the buttons have been spaced apart and enlarged.
This is a short term fix, because we have a new board UI to release soon (very close to entering testing after a rather prolonged development period), with different buttons anyway. Its a big update and should lead on to quite a few enhancements.
I'll resist predicting a release date, as estimates so far have been wildly optimistic.
edit : And it will be tested on iPad before release.