When using the measure tool on a hex grid, all directions don't seem to be created equally. After fiddling with the scale (setting it to 0.93 seems to result in a true 1 meter hex grid) I found that measuring along the diagonals seems to produce longer measurements. The same effect can be seen with the default setup as well. 
 
 Test system:
 Windows 7 (64 bit)
 Chrome 21.0.1180.89
 
 This shows up consistently on several systems. 
 
 Also, is the fact that I needed to set the scale to 0.93 a bug? It seems that setting the grid scale to 1 m should result in each hex being exactly 1 m apart.