I'm not a pro at this, but my parent's 3 of my parent's F-150s did this a time or two after not being driven. The dealership said that there could be condensation in the fuel lines. After letting it sit for awhile it was fine. This sometimes happened when the temps were below 20 degrees, which isn't that cold.
Try it again later, if it doesn't start by turning the key; try to pop-start it. Put the key in the "run" position, try to get it rolling forward, put it into first, with the clutch depressed, pop it out all the way. If the car starts push the clutch back in to keep it running.
