Well changing the oil tonight I noticed a very small drop, but a drop
nonetheless, of coolant on the center bottom of the passenger side
head, at the rubber gasket.

PO said the van had recently had new heads, this claim supported by
the cleanliness of the heads, brand new pushrod tubes, etc.  So --
what's my best first action to address this?  Do the heads need to be
retorqued after they are run in for a while?

Or once they start leaking is it a lost cause and they need to be
pulled and re-sealed?

Allan