In other areas of breeding this is considered a Bad Thing.
Marijuana seed sellers and buyers seem happy at F4. (Filial generations) F1 = children of parents, F2 = grandchildren, F3 = great grandchildren, etc. At F4 the strain is not stable, but this is marketed a feature, like an Easter egg hunt with an emphasis on the wonderful hybrid vigor. Surprise, you don't know what phenotype you are gonna get! By comparison Tomato growers would considered F4 seeds to be unfinished, ok for sharing with other breeders but NOT ready for the general public. F7 is considered genetically stable for everything except marijuana, but that would requires 3 more seasons of work.
http://kdcomm.net/~tomato/gene/genes2.html
Thanks for the link HubbaBubba, that was really interesting. I read about a 1:1 or 2:1 CBD strain(ACDC?) that presented with high CBD/no THC in 25% of the cases, high THC/no CBD in 25% and high THC/high CBD in 50% of the cases, does that imply an early generation? Would it be possible with continued breeding to reach a 1:1 ratio in 99% of the cases or is there something else going on?