Yeah, dealers don't care as much anymore. Prolly offer a little less in the trade and then sell it for more than one w emissions.
OP, you state a light has been on for 3000miles, so it doesn't affect drive ability?
Is it using def and regen ing? Because serious problems don't usually let the truck keep operating fine.
All that said, deleting is a sure fire option to be rid of all emissions problems and I'd do it in a heartbeat if the emissions started costing me money?
No local shop re flash c rap though unless you know what you're doing. Get the tunes from a reputable name brand that has perfected the tuning and has good tech aupport. Aka EFI Live