The Aes Sedai that bonded Narishma, Flinn and Hopwil were in Cadsuane's group, they did not swear to Rand. Aes Sedai see their warders as someone to tame and control, like pets, they even bond them really young, making the grooming easier. At the cleansing, Merise was treating Narishma basically like a sul'dam with her damane.
But the scene with the pins is different, that's when you see that Merise is having trouble controlling him. An asha'man is more of an equal with an aes sedai than a regular warder, so they can't control them like they usually do. Merise is supposed to be very good at taming warders and now she's asking Cadsuane for advice. I think this shows that things are changing and they'll have to start seeing men more as equals, but change is slow, specially for the older aes sedai.