I had mentioned this some time back and again last week:
Originally Posted by GUWonder
TSA's "managed inclusion" can lead to somewhat longer/slower PreCheck screening. Also, TSA can still sometimes shut down PreCheck LLL screening outcomes for passengers even when PreCheck LLL is indicated by the boarding pass scan.
The increased use of dogs/swabs and the use of the voodoo "security" "behavior detection" nonsense is part of the "managed inclusion" related changes to boost usage of PreCheck lines, which are rather underutilized.
http://www.flyertalk.com/forum/20985267-post1434.html