1. Check the adjustment knob near the steering wheel (left side) that controls the lighting of your gauges and radio. Flip that around a bit to verify that the problem isn't from little bugger shorting.
2. Do you leave any items on your dash? Those kinds of things can roll over the light sensor. I haven't gone outside yet to verify where it is but most sensors are centered and closest to the windshield.
3. More unlikely, but check the settings on the radio. This probably isn't your cause just because it's more likely the radio is receiving the input to make the changes to the lighting from the steps 1 and 2.
Because you said your dash AND your radio are doing it it's probably step 1.