That little bit of yellowing may actually be a result of the co2/nutrient/light ballance that Hick is talking about. Whenever you increase one of the growing variables for the plants, the plants will react and what ever is weakest in the line of variables will show up as an imballance which can cause a bit of deficiency or growth pattern change.
The bigger leaves is just the phenotype expression of the indica side of the hybrid. Typically, Sativa has long narrow leaf fronds, and the indica has shorter, wider leaf fronds. With the hybridizing of the 2 types, you can see the experssion of traits from both sides come out at different times. I have plants that come from the same clone mother (Blueberry Punch) that have shown a good bit of variation in the leaf patterns and a few other traits as well, but the overall plant is fairly stable.