Do sativa's buds grow till the end?

[Escartajo]

Hello

I got 3 blue dream plants on their 5 week of flowering. One of the plants suddenly stretched in the 4th week and many of the pistils started going Brown, whereas the other plants Just kept the sale and had no changes whatsoever.
Now that im writting this im becomming amaré that the question rather than if sativa keeping on growing their buds till the end is, was this sudden changed normal?
What should I expect?
Even so, until which week Will my buds keep on growing?

Thanks!

[Ben.g]

I know sativas stretch more, but thought they stopped after so long?

You have me worried now as I thought mine had just finished stretching. Ahhhh