Context as Cannoli said is everything. When Elayne was calling Mat "Master" it was pegging him in a social hierarchy. She was effectivly labeling him as a commoner and herself as a noble hence he should defer to her being his social superior. This was why he was annoyed.

She tried the same with Taim but he came to visit and it was part of her way of tring to put him in his place. Taim is a very different fish from Mat and his little smile shouted "I'm the most dangerous and powerful person here, what ever you want to call me"

I think the honorific for the Aes Sedai in their own mind is a bit like calling someone a senator or member of parliment. Technically they serve the public, they are suppost to be public servants but they effectivly help run the country.

As far as the typical Aes Sedai mindset goes I think its something a bit like - 'Servant equals servant of all which equals my job is to look after all of you and to do that you have to do what I tell you to do, follow my orders I've got your best interests at heart and after all you are a bit like a child and don't really know what is best for you'.