It wasn't hinted at in the solicitations, though the cover indicated that something was up. But the back cover of today's DC Nation #4 has a question to ask of Action Comics #1003.
Who poisoned Superman?
ACTION COMICS #1003
(W) Brian Michael Bendis (A) Yanick Paquette (CA) Patrick Gleason
How well does Clark Kent know his own city? Are the threats targeting Metropolis new or something older and more dangerous than they seem?
With mobsters being killed off and the Daily Planet staff hunting for answers, it's up to Superman to discover what lurks in the underside of the city he thought he knew so well. Who is the Red Mist, and why has Superman never heard of someone so powerful and dangerous? And what is Lois Lane doing with Lex Luthor?In Shops: Sep 26, 2018
Something else to note – in the comics it has been Red Cloud not Red Mist. Was the character originally called Red Mist? And then someone pointed out that this was the same name as the character in Kick Ass who would later change his name to The Mother F-cker? I really think that might be what happened…
And certainly the kind of fellow who would have no qualms swinging around a lump of kryptonite…