When Siuan says that last though, it must be since Moiraine LAST left the Tower? I mean, two messages in 20 years? To the only other person who knows what you are doing?
And now I also really want to know what on earth Moiraine did that she needed Healing? But not immediately, since Lan was...
I think she says she has only heard from her briefly in 20 years.
There is also a reference somewhere in the books that Lan carried Moiraine to the Tower to be Healed. I think it was Anaiya who says something about her being away too long "this time".
So she has been back to the Tower a few...