Moisture detection (Non-Invasive)

What are some conditions that could exist, that could give a temporary high level of moisture, even when the surface has no signs whatsoever of moisture?
Recent Paint, etc. ?? Roof, Eaves checked on exterior, all fine, it did appear to have some recent painting.
Any thoughts on this would be greatly appreciated.
Thanks in advance for your help.

More information would be useful to answer. How did you determine there was excess moisture? Do you have something to measure the relative humidity? Are you using a moisture meter?

I carry three tools for moisture checks. A RH sensor with temperature digital display, a moisture meter with pins and pad and a thermal camera. I’ve caught myslef when humidity is real high and toilets, tubs and even kitchen sinks had been sweating befoe I started looking at things.

Mack I’m not exactly sure you are asking, but metal behind a surface can give a false positive. The most common example is metal corner bead behind drywall.