Falling Sand Position Offset Sometimes when Summoned

Put this command in a command block and set it up with a redstone clock:

/summon FallingSand ~ ~2 ~

{Time:1,Block:stone,Motion:[-0.6,0.7,0.4]}

Watch and wait and you will see that approximately 1/50 blocks summoned will be in a slightly offset position, even though the command is summoning the same entity.