UNWITNESSED ACCIDENT. OPERATOR CLAIMS WHEN DISMOUNTING FROM HAUL TRUCK, FINAL STEP TO GROUND WAS FURTHER THAN ANTICIPATED. WHEN LEFT FOOT CONTACTED GROUND HE FELT PAIN. OPERATOR CLAIMS HE REPO RTED INCIDENT TO SUPERVISOR, BUT SUPERVISOR HAS NO RECOLLECTION OF SUCH. ON 2-21-00, OPERATOR CAME IN TO FILL OUT AN ACCIDENT REPORT COMPLAINING OF NECK PAIN.