Coordinates in F3 not same as in game

/setblock with Command Block or Chat not corresponding with coordinates shown in F3 mode.

What did you do?
I went into creative mode on a new redstone-ready flat world. I used the /setblock <x> <y> <z> command (with actual coordinates of course).

What did you expect?
I expected my block to be placed at the <x> <y> <z> coordinates that were in F3 mode when I was standing in the correct location of where I wanted my block to be placed.

What happened?
The block was placed two to five blocks away from the desired location. Adjusting the /setblock command in the correct direction worked. However, the /setblock command ended up having to place in a spot different from what was shown in F3.