tranny seal 833

i just did the clutch in my 72 duster last week , i was in under it today andi see oil in the inspection cover cleaned it up went for a ride for a few hours ,came back and checked it and there was some more oil in there. it looks like the front seal in the tranny ,though i changed that to at the time i did the chutch ,note i did not change the piolet bushing ,could the input shaft be moving up and down casing it not to seal any one have this happen to them thanks