alpaca and llama felt quickly. If you store it sealed in plastic, it will not be able to breathe. As it warms up, you will have condensation occur (from the fiber itself, not from the outside). When it cools off, warms up, cools off, warms up, cools off, you are creating an optimum condition for felting.
i like storing my fiber in pillow cases.
Be sure to keep separate the 'blanket' or prime from the sub-prime (like the neck area) and use the belly, britchen, leg wool for mulch.0