It’s probably just genetics…..pistils can turn color for lots of reasons. It doesn’t look ready to the naked eye, as the calyces don’t appear swollen.
Usually if a plant is pollinated, the tips of the pistils will turn brown but not the entire pistil.
When did u get the plant? I’m assuming it was flowering when U received it? Were the pistils white? Strains can have a different look growing outdoors and pistil production can really vary.
Get yourself a $10 jewelers loupe and really examine the trichomes on inside of the buds….the ones on the bracts & calyces. Those are the trichs that matter. The leaf trichs degrade faster and will be cloudy band amber long before the buds are ripe.
Also, a pic of the whole plant would help. Good luck.