I did a brake job on my 2002 2500 Dmax. The back brakes on the right rear were down to metal to metal. Put on a new rotor and pads. Now to the front. There were a lot of pad left but changed them any ...
The front brakes more under HEAVY braking. The proportioning valve assumes enough weight transfer has occurred and send more hydraulic pressure forward. Under light braking, most modern trucks/cars use the rears more.
Now if the fronts are actually cold / lukewarm, there might be a problem.
Have you tried hard (threshold of ABS) braking and then carefully feel the front for increased heat?