My first rule of baler monitor moisture readings is: don't trust them!
Maybe it's because they are reading mostly hay from the outer edge of the swath, I don't know. I rely on the probe and use the monitor as a guide. Strangely enough, our 605N tends to give a reasonably accurate final reading for the completed bale, even though the moisture readings while making the bale appear to be generally inaccurate, normally reading drier than it really is. Go figure.