Im posting a helpful hint... turns out this hint isnt new for Acad 2013, but it must be set to ON by default in Acad 2013, because the setting is at least in Acad 2010.
I just installed and been using ACA 2013 and everytime i try to drag a wall style to another wall it automatically snaps to the justification line. I searched the AEC option settings, and clean up radius's of AEC walls to no avail. VERY frustrating.
if you go to your OSNAP SETTINGS dialog box there is a check box for:
"Allow general object snap settings to act upon wall justification line"
Un-Checking this will allow walls to snap to back side of walls and not thier justitification lines...
hope this helps someone else.
ccastelein