Brown stigmas or pistils?

As long as it isn't too early, not likely an issue and normal. Pistils do die, turn color, and coil up / swallowed by fattening calyx around it. It can also be a sign of pollination. You'd have to look around and consider context to eliminate that as the cause. e.g. i don't worry about pistils turning color as i near 42 days of flower, give or take... development rates vary. You'd see issues n leaves before pistils, if nutrient related... not sure if tehy can be affected by such a thing under normal contexts... dumpster fires excluded.