Recently Balashov, Martin and Crowe reported on measurements of the angular dependence of the resonant part of the transition matrix for auto-ionization from spherical symmetric states. When post-collisional interaction (PCI) is neglected, the resonant part of the transition matrix for this kind of collision is independent of the electron emission angle. On the other hand, when PCI is include in the theory, an angular dependence becomes evident. This is illustrated by calculating the effect of PCI on the resonant part of the T -matrix for auto-ionization from the spherically symmetric state. It is argued that it is the distance in momentum space rather than the real space distance that is decisive when PCI effects are important.