I don't think the virus thing is canon. All that Worf ever said about the head bumps was that Klingons didn't like to talk about it with outsiders when Bashir posed the possibility of a virus and O'Brien posed the possibility of genetic mutation. So he never confirmed or denied either, right? I can't believe I know that shit tbh.

But you're right that they did indicate there had been a change and stopped just ignoring it, good call!