Not exactly sure where your focus point was, her face I assume. Your DOF is small of course but you may have also have not been square to the subject. This will cause what looks like OOF at the edges. (Removed Link as per Forum Guidelines)
The good thing about 24-70/4 IS is that it already focuses very close, if you need to get even closer, you turn the zoom ring past the 70mm mark and it will focus even closer. [link removed per forum guidelines]