An honest answer:
For the most part, darker mucous indicates "stagnation" due to time left in the body, but does not necessarily imply that this is an infection. Since the mucus is coming from your nose and not being coughed up from the lungs, it sounds like there is something going on in the sinus. The best thing to do in this case is try some saline nasal sprays and keep an eye on it. If the orange/darker mucous keeps up, you will need to see a doctor. Persistent, orange/dark mucous could indicate sinusitis.
Do you have any pain in your face?
If this keeps up for more than a few days, there is a good chance you have a sinus infection.