Odd noise under load

[Wannabebad]

Hey guys I rarely post typically just gather info on here. Anyway, I occasionally pull a 16' trailer with my tractor loaded (midsize kubota) which I would roughly estimate to be in the 4k-5k range total load. Anyway my 2014 5.3 occasionally makes an odd sound when under load very metallic in nature. Could be a lifter? Or is this a DI noise? Seems to be focused on the top end of the engine and directly infront of the steering wheel. I rarely hear the noise when pulling out empty or accelerating hard though I think I am becoming somewhat hypersenstive to the noise and hear it all the time now. Also, it is usually most noticeable when I am in town or in a cut on the highway where there is something for the sound to refelect from. Any ideas? Should I get it in and have it looked at?