FallingSand glitches upwards

Falling sand with custom motion, after about 1.5 seconds, adjusts itself upwards. Go on any world and use this command:

/summon FallingSand ~ ~ ~ {Time:1,Block:stone,Motion:[-0.6,1.0,1.0]}

You'll see that after it starts falling back down it's corrects it's position by glitching upwards.