Got the same thing happening (3 or so quick clicks just on the first start of the day). Tried to isolate it by poking my head under the hood for a few days while my wife turned the key, but no luck. Maybe it is just the sleeping mice getting thrown around by the serpentine belt!
97 F250LD SC 5.4 4x4 White, fog lights w/parking lights, piston slap, driver door crack, no gutter cracks, on it's last legs, donating various parts to the F150 below
07 Expy EL EB 4WD that everyone wants to drive!
02 F150 SC 5.4 4x4 7700, nerf bars