<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by cAAl:
It does make you wonder what caused the miscalculation in filling up the tanks. Was it late arriving passengers? Unexpected cargo? Bad math?</font>
I think it's a timing issue. The fuel typically is ordered and loaded before all the passengers, baggage and cargo are loaded. Obviously, in most cases the airlines have a very good idea what to expect in terms of load factor, but sometimes they get it wrong.