quick advice please

ok so my girl has been flowering for a good amount of time, dont no how long at all seems like 4-5 weeks tho.
about 85% of her pistils have turned and i just flushed her about 2 days ago.
her buds are still growing even tho the pistils have turned, but since i flushed her the buds are starting to turn a purplish color.
could this just because its starting to get really cold out in the morning and late at nihgt?
should i just harvest her now?
thanks alot