Does a grain of salt have exactly equal amount of sodium and chlorine?
Crystal solids, however small, have defects in them. These defects are basically irregularities in the arrangement of constituent particles. They are of two types:


Point defects 
Line defects.


Point defects themselves are divided into other kinds of defects. Here, I'll explain only the relevant one.

One type of point defect is a vacancy defect in which some of the lattice sites in the crystal are vacant. This means that some atoms of Na or Cl or both are missing from their lattice sites. 

So the answer to your question is, yes. That scenario is very much possible.