When you summon a FallingSand-Entity with a command block, which is a rotated log (I mean a horizontal one) the textures get placed on the correct sides but are not rotated.
This also applies to every other block, that can be rotated.

To reproduce:
Type in chat or in a command block:

/summon FallingSand ~ ~2.5 ~ {TileID:17,Data:6,Time:1,DropItem:0}

and trigger it.
As it flies, the textures are not rotated, but as it lands, it corrects itself.