2003 Ford Ranger grinding noise

After I had my front rotors, calipers and pads replaced everything seemed fine. During normal driving conditions (for me which is 12 miles to and from work and a few short trips around a small town to run errands) everything is good and quiet. But after I drive about 50 or 60 miles of highway driving and start to slow down into stop and go city traffic I start hearing a grinding noise when coming to a stop in city traffic. This only happens after an extended trip on the highway. With new all new rotors, calipers and pads it doesn’t seem like it could be the brakes. What could it be? Wheel bearings getting hot?

How long after your new brake job did you notice the noise? Was the noise present before you replaced your brakes? Go back to the shop and explain to them what you are experiencing.

Without more info it’s hard to be real helpful, but it could be that the flexible hose that carries brake fluid to the front wheel caliper is deteriorating inside and the new caliper is not releasing fully. This is a real shot in the dark theory, and you should do what @COROLLAGUY1 suggested.

you didn’t specify, but judging from your question is it safe to assume that you hear the noise from the front of your truck?
Were the bearings serviced when the brakes were done?