not abnormal. is this a clone? if not, expect differences. heck, even with a clone lots of factors can cause this to happen early.
one of them is being pollinated. give a good look over the canopy.
i've had pistils stay white until harvest. other times they are mostly brown by 42-49 days. -- no seeds in these examples, of course. This is why you dn't use pistils to determine when to harvest. it is correlated, but not causal to that end.