I just had my lower unit oil changed last tuesday.now its leaking a little out of the top hole. the plug is tight.I was watching the mechanic change it after he took out bottom plug and drained it.replaced plug and started pumping oil in top hole,he pumped for about 15 min and said for some reason it dont want to fill,maybe the oil is just cold,he was still pumping.then it spewed out fill hole ,he said thats it. could it just be overfillid.is that bad for it? should I just watch it to c if it stops leaking or take it bak to shop. my local cabelas.