I recently put out a post about having to get a new Catalytic Converter at only 16000 miles, anyway, finally got the truck back from the dealer a week later, but not only did the CAT get replaced but also the DPF filter, Dealer said it was a good job that it was under warranty, he said that the DPF filter was clogged with soot and needed replacing, I am worried that this might happen again, don't see much about it online, warranty runs out in a few weeks, what other reason could cause the soot? They said the engine checked out fine.