Item drops spawn randomly.

unfortunately I didn't took a screenshot of this,
but I was mining an underground tunnel and found out alot of stone and dirt floating on the ground above the tunnel. about 10-7 blocks high then where I was mining.
More then that, i found out that when i break hoppers they sometimes spawn 5-4 blocks away and even spawn behind the wall if you break it next to a wall.

this is happening on server, not SP.