Please remember that anything expressed by me reflects my own opinion at this time and does not speak for AA as a whole.
A “Dry Drunk” can be a person who will claim to be a member of AA and who does nothing else but show up and pay it lip service. It can be a person who does just enough to make the pain go away and become comfortably "miserable." Through personal experience it was when I started putting other things before my program to where I became separated from the “sunlight of the spirit” as it is described in the Big Book. Let me emphatically tell you that anyway you look at it, it’s not a place that I want to go again, because I might not survive it the next time. (The only thing I didn't do was drink, but all my indexes of maladjustment were back in force.)
It can happen at anytime in sobriety. When it hit me I was 13 years sober. The best defense against it is to work the steps and make sure that when you have reached the last three, the maintenance steps, you DO continue to improve your conscience contact with God on a daily basis. (A good thing to do is Daily Prayer and Meditation. Real improvement comes from MORE prayer and MORE meditation... and working with others.)
Just a thought.