95 Freightliner N14 fuel filter...

That looks like oil residue, not a leak, or moisture . Not a big deal. Also if that line were rubbing on the steer shaft , the shaft would have a rub mark around it from turning the truck and driving. Think you are being way to picky. Or just no experience with older engines etc.

 

Yep, guess I should edit a question mark. Just looking at a picture.
I had a fuel line look like that one does. It would saturate with fuel. Replaced it. When I took it off the hose broke when bent in half.

If it is moisture, from where? Moist from ECM to firewall over frame rail and the two hoses that go to his fuel filter. Valve covers look normal. Maybe the OP just sprayed that area to clean? IF not, I think the return fuel line is saturating the area with moist fuel. The hose might even be frayed a bit.

It also looks like he might have a power steering leak on his steering sector by the input shaft. Road grime caked all around except where fluid might be coming out. Just a guess. Maybe the OP just greased his truck and wiped that area with a rag.

OR maybe my old eyes are deceiving me. It is just a couple photos. Easier to tell in person.
Not to picky for my truck.
Maybe looking at some one else's truck this might be too picky.

Good luck to the OP, I wish him well with his truck.