Is it a problem if the framing is 4" short of the edge of slab foundation?
If when everything is done, the slab will have an exposed horizontal surface, then yes, that is incorrect. Either the plans were drawn incorrectly, or someone didn't follow them. Whoever made the mistake should be responsible to fix it.

At this point, your options are to rip down the wall and fix it, double the thickness of the wall (weird) or remove the bottom row of siding and install flashing.