Funny thing is my little 273 was doing the exact same thing.
Just a little puddle. Nothing at idle, just after a freeway trip.
I just "snugged" the valve cover bolts as they did not appear to be loose but
to my surprise when I put a wrench on the intake bolt it was way loose.
So I re-torqued all the intake bolts and like I said earlier re-checked the valve cover bolts and that seems to have cleared it up.
I agree with Rusty here, I'd go ahead and do both, it won't take long.