It seems for me that 70 degrees ambient temp is the cut off for any regen issue.

 

Wife told me it happened again last week while she was driving, said she was 10 minutes from the house when it made noise, and when she pulled into the garage she could smell the hot DPF. So it was definitely in regen.

Temps were in the 40's at the time. I try to pay attention to when/where/what any time it does that, whether it's when I'm driving or the wifey.

I keep checking the TSB's to see if anything changes. They just keep updating the same one every few weeks and it still says the re-flash is coming 1Q 2016. I think last update I saw was dated Nov 16th.

 

I have not noticed any hammering.