Could be residual oil left over atop the skip plate. Try cleaning the top of the skid plate with some engine degreaser or brake cleaner wherever you can reach and rinse it off with a garden hose. Let it dry then park your quad with a piece of cardboard underneath. Then keep an eye on it to see if it still leaks.
I have after install. But I cleaned agin. I talked to the local dealer and he said sometimes aftermarket axles and seals dont match un it could be a millimeter off. For me to pull them back off and he whould measure? Does that make any since??