Yes, the break down of Monofilament from UV light rays and Sunlight is because it's Outdoors. If the Mono is kept indoors it's "self life" will be considerably longer.. Even in a Building with skylights and plenty of windows, the Monofilament will last a Great deal longer.
Even if the glass is not listed as UV protective, the glass still defuses UV light rays a small percentage.. many modern Office buildings have UV protection windows installed - and short of asking about this, One would never notice..