Leaky 340 Head Bolt?

Nothing in those pictures even counts as a leak in my book. The little bit of residue in the picture could just be left over from before the valve cover gasket change, even if you cleaned it up once the engine heats up any oils trapped in the crevices will seep out again.

Definitely do not remove the head bolt and put a washer with RTV on it in there. Not only will that not fix anything, it could screw up your clamp pressure on that head bolt.