It would seem unlikely that a 2009 Wood 133 would weigh under 7.1Kg - and if it did (does) then it certainly is well UNDER the weight tolerance range of the 133.
Regarding the weight difference with Wood+Carbon (in 121 size) the saving is typically about 400-500grams - and the performance difference is achieved not only by weight reduction but also by the more direct structure of the carbon board (in the lighter wind/flatter water conditions range).
As you will be aware, there is a certain weight tolerance range on all boards that are produced, (typically +/- 5% ) and usually in turn based on an average weight (which is often determined only after a certain qty of each size/type has been produced in order to confirm a true "average".
The Wood+Carbon is a premium product ; should you be unsatisfied with any asect of your purchase, please refer (in the first instance) thru your supplying dealer (or importer) for their check/investigation and resolution.
Cheers ~ Ian