A few things you may not have known:

[The Jungle 1]

65. Maybe maybe not.

I find this expression comes from the early 1900s and originated from newspaper printing.
The printing presses used in producing newspapers were very large and operated at a high temperature. Just as a copy or printed page is warm coming off a laser jet printer, the “news” coming off of these printers was literally hot. I have not been able to verify if they used heat set ink.
Heat set printing ink is made for the offset printing process. It is made specifically to deal with high speeds and a quick drying process that is accomplished by means of a heat set oven. I don't see how they could have had high speed printing without ovens.
The Linotype machine you refer to produced the lead type. It cooled and was set for printing. When the printing occurred the lead was already cool. The Linotype machines were still in use in the 60s our local paper had one. We went to see it on a Scout tour.