Drain Plug Leak

I hope someone can help me. I have a 2003 KDX 220 and am having trouble with a leak at my drain plug. There does not appear to be a crack or any stripping. The leak is very slow. The washer and plug appear normal. It is definitely coming from around the plug, so no case gasket issues. I plan to change plug and washer( to copper) but i was wondering if anyone has seen this before.
P.S. Just started riding again after 15 years. Love this site

Huh, that may explain it. I have changed oil 4 or 5 times with same one thanx. hope thats it