Ok guys. I've had this issue in the past as well and it's gone away since the weather got cooler. My 12 was built in April 11. My ford parts catalogue seems to say the part cutoff on the older one for my car (CV6Z-A) is from 1/31/11 to 3/19/12. Hope this is of some help.
'12 Blue Candy 5spd SE Sport- On Eibach Pros, Enkei Ammodos, Steeda STS, Steeda CAI, Ecoboost rear muffler