737 weight/balance question
This happened to me yesterday coming back to sydney. I was on QF1104, and extra service put on due to fog in Melbourne on sunday night, it was a 737 and me and the missus were sitting in seats 1D and 1F. After about 20mins sitting there a flight attendant came up to us with new boarding passes and said that due to weight/balance distribution she has to ask us to move to another seat. We had no problems with this as this can be expected when travelling on a staff ticket. The new seats were 13A and 13B. There was only about 25-30 people on the plane and most (90%) of people were sitting on the left hand side of the plane. Noone sat in seats 1D or 1F for the rest of the flight. Looking at the seat plane for that aircraft theres only 24 rows, so we were around the half way mark.
Could anyone shed some light on the reasons? Im presuming cargo was on the right hand side of the aircraft? Could that be why? But then again why would 2 people matter on an aircraft that was nowhere empty? Help is needed, as Im trying to understand the technical side of it.