If what you say is true, then a lot¨of what Verin writes in her letter is lies. Lies that serve no understandable purpose. Why lie and tell him she planned to return within the day? Why lie and tell him she expected him to open the letter after after just a few days, when it serves no purpose after the fact other than making her appear foolish? Why lie and claim that she expect Caemlyn to be lost before the month is out if her entire plan relies on Mat doing nothing about it before 30 days (I don't remember how long WoT months are, but that sounds like cutting it awfully close, if not outright being too late)?