Check for plumbing vent pipes in the walls around the noisy area. See if they have rubber expansion couplings visible in the basement. I have heard noise when running hot water and the drain/vent started to expand in length and rub at the floor or wall transition. Cutting the pipe and installing the rubber couplings stopped the noise as the coupling absorbed the expansion.
It does not have to be hot water related. It could be the framing contracting before the next days warm up and expansion. Have you ever seen plumbing vent pipes on the roof where the exposed painted portion has pushed up above the boot exposing unpainted pipe. This is likely related to exapnsion and contractin of framing and/or pipes.