it makes sense if you think about it - if you have short cycles you ovulate earlier than the average 14 days, so you've been pg for a bit longer so baby comes out sooner. it's the other way round for long cycles, you ovulate later so the baby's born later.
Short cycle (26 days) and ds was born on due date. Actually 3 days late if you take into account short cycle and leap year (doctors' cardboard calculaor thingies don't allow for the xtra days of a leap year!). I know when I conceived as well!