This is a hybrid between N. ventricosa and N. alata, the former being a highland pant and later an intermediate plant. It will give you larger pitchers and darker colored pitchers in cooler conditions.When the plant is moved from the nursery to your home, it will take some time to adjust to your home environement. As such the first few picthers if any will be small. But since yours is giving you pitchers, it is a sign that the conditions are right.