Those are definitely preflowers but still just calyxes, so it could still go either way. Keep an eye on them every day in case they're males and you need to pull them.
So how old is this plant? (From seed, from germination, from coming up?). What you have, is a plant that would've been kept in the autoflowering strain selection process. That's all auto flowers are, plants that finished way faster than their brethren and were kept to pass on their speedy genetics. After several generations they can get them pretty stable.
