This is really pointing in the direction of a bad instrument cluster. It's actually a complete computer that operates a number of things, and has the drivers for both the dome lights and dash lights. It also has the drivers for a number of other things (like almost every interior light). I am not 100% sure, but I believe the dealer can hook into the system and run diagnostics on the cluster to determine whether or not it's failing.
BUT - before you spend a bunch of cash on diagnostics, try doing a full reset. Disconnect your battery cable for 30 minutes (over night is even better). When you re-connect it, all the computers in the truck will reset. Like your home computer, sometimes issue can be resolved by rebooting.
Bad part of a reset.....the clock will be wrong, and your radio presets will be gone....along with your memory seat positions, etc. Truck might run a little weird for 5-10 minutes while the engine computer learns the sensor input. If you do this, a short highway run (10miles) is a good thing.