If you changed the oil and then heard it, I think they had it full of 15w40, that would have kept the phasers from ticking so bad. 5w-20 will tick any time after warmed up.

Krewat, Yes they have lash adjusters, but ,as you probably already know, the sound that those make can be intermittent when they are bad and way different from a traditional lifter. also, lash adjusters will make noise off idle, where the phasers usually don't from 1500 and up rpm. I'm sure the OP is hearing the phasers and the dealer was doing whatever he had to to sell the truck.