Mercenaries 2: World in Flames Weird Phenomenom

I have noticed while playing my new game Mercenaries 2:World in Flames that there is a strange phenomenom. After exploring the foothills near your Private Millitary Company HQ I came back to the road and found an empty "Chopper" motorcycle. It has happened about 5 times to me and I felt an ure to tell the public. If you own this game, be on the lookout for "Ghost Choppers"!