Brakes dragging question

[rockyrivermark]

1970 C10
350 auto

So I'm still getting a dragging on my front disc brakes but it only happens when the engine is hot or I'm driving around a while. It's not severe but rotors are very hot to the touch after I go on a 15 min drive.
Finished the restoration this past June. Truck sat for a few years before I bought it this past year so I replace most of the braking system parts
Replace parts
New Front calipers
Rear wheel cylinders
Calipers brake hoses
Master cylinder
Adjusted master cylinder push rod
Master cylinder is not over filled
I've read that the brake fluid can get a vapor lock from the hot engine bay and the article suggested a performance brake fluid to help with this it's called Pentosin dot 4.
Entire system is bled and bled fine.
Thanks for any into or ideas.
Thanks
Mark