07 LMM:In the past month, I've had the "Clean Exhaust Filter" "See Owners Manual Now" message come up while towing a trailer on a road trip. As expected, the DPF goes into Regen mode while maintaining highway speeds for 15-20 minutes, and the message clears. The second time this happened, it set the P2459 code, which cleared itself a day after I disconnected the trailer and resumed normal driving. My question is, is this something to be concerned with? Does this mean my DPF is about to be needing a replacement? Any insight would be greatly appreciated.