0918 oil2
Oil traders work on the floor of the New York Mercantile Exchange on May 11, 2012 in New York City. - 

Mid-day yesterday oil prices dropped three dollars in about a minute -- and they have kept falling ever since.

Was this a computer error -- or someone's "fat finger" on the button, as they say. Or is oil falling for a reason?

Samuel Chishook is a consultant with KCB Energy Economics in London.

Follow Jeff Horwich at @jeffhorwich