So at one point, Liandrin starts using the power on Rand to get him to tell what he was wiping off the walls (though why she needed him to do it is anybody's guess). About a half a second later, she drops the power and Moraine walks in.  Given what we know about women sensing the power, how come Moraine didn't sense that Liandrin had channeled very recently?  Even if she didn't know exactly what she had done, she probably would have had some questions and I doubt that she didn't know she had been doing more than channelling light.

I think you can only tell if someone has been channeling using the a'dam.  I don't remember it anywhere else about knowing when someone had channeled.

Morainne would know if liandrin was channeling while it was happening.  But she wouldn’t know what she was doing with the power, just the relative amount that was being used.  And how far away they were apart would affect how noticeable it was.    

 

Sensing if the power was used in the recent past is only possible through reading residues, only a few channelers are able to do that. It’s a rare skill.

 

someone will correct me if I’m wrong, but I think that’s how it is.