A lot of people stop giving veg nutes during flowering - this will inevitably lead to yellowing of leaves. A lot of people also flush plants grown in soil and give no feed at all for the last 2 weeks or so - again, this will lead to yellowing of leaves. Both of these things are wrong in my opinion.
I feed right up to the last watering when growing in soil, and have noticed no drop off in the quality of the finished buds - in flavour or smokeability. Some strains and phenotypes will still experience yellowing - but most won't in my experience. I strive for my plants to finish as vivid green as when they were in veg - because the finished product is just as good if not better and the plant won't have had to struggle just at the most important point.
If your plants are soil grown and ready for harvest and still vivid green then you've done well in my opinion. Harvest and cure correctly and I'm sure you'll have a quality product.