I'll start this off by saying I am no brake expert or even a mechanic.
I have seen similar things happen in vehicles I have owned and it seems to correlate to having high carbon steel brake rotors. The rotors seemed to develop a light coat of rust on the whole rotor including the braking surface pretty quickly. Then the first time I would brake each day it would be a little rough and grabby. Once the thin layer of rust was knocked off, things were fine. If you look at the braking surface of your rotors in the morning before you move your truck I bet they will be lightly rusted and after you drive to work they will be free of rust. I am led to believe this is normal for cheaper rotors.