Moving platforms enable sparse arrays to assume higher degrees of freedom and lead to increased number of lags. In essence, array motion can fill the holes in the spatial autocorrelation lags associated with a fixed platform and, therefore, increase the number of sources detectable by the same number of physical array sensors. In this paper, we consider coprime arrays, and assume quasi-stationarity of the environment, where the source locations and waveforms are considered invariant over array motion of half wavelength. Expressions of the synthetic array comprising the original coprime array and its shifted version are derived, and analysis of the difference co-array corresponding to the combined array positions before and after motion is provided. It is shown that majority of, if not all, the holes in the original array position are filled by a small translation shift along the coprime array axis.