The short answer to both questions is No. However, it is not possible with standard Varian probe mounting hardware to precicely reposition the probe, so you should expect slight changes to the shims even though you think it is in the same place. Bruker probes are much more easily returned to the precise same position as before removal, so long as the upper stack is not disturbed. When moving a probe there could be slight, short term SC shim current changes induced by eddies, but they will equilibrate back to their set values after the eddies stop. RT shim currents will not change from eddies, because they are actively regulated.