Workbench icon appears in place of the grass block icon with new launcher in 1.6+

Search has shown no similar report for the launcher.

I thought that snapshots having a workbench icon in place of the grass block icon was to indicate that they were still being "crafted;" i.e. were development versions. However, 1.6, .1, and .2 all have the workbench icon.

Is this a launcher bug (like neither showing for 1.5.2), a game bug, or not a bug at all and just an odd change for no apparent reason (seeing as the grass block was iconic as the icon for the game)?