First, It could be residual oil left over from the leak. Did you put it in the water and run it after the pump was replaced? If not, oil can be trapped at several points in the lower cowl, mid-section, etc. Second, if you did run it, you might eyeball the pump. You can generally see a drop or two of oil hanging on the lower side near the lowest screw. If so, it is leaking again. You might try an allen wrench (I think that is what was used) and make sure the three screws are tight. If not, that might fix it quickly…