i dont think it would start shedding if nothing has changed... can you recall? overwatered? change in lighting? etc?

Leaves shed due to any of several potential causes. Older leaves shedding is often from a decrease in light levels that occurred in the not too distant past, nutritional deficiencies of the mobile nutrients in particular (N, P, K, Mg mainly), root congestion, a high level of dissolved solids (salts) in the soil solution, or root congestion are the most common causes. Chill, and especially sudden chill is also causal when we get into the colder months. Though it might initially seem strange, a drought response from over-watering or under-watering is also a major cause of shedding. Over-watering inhibits the plant's ability to take up water; this, due to an insufficient supply of oxygen needed to drive the uptake process. When we over-water, the plant's chemical messengers tell plant central that it better initiate the survival mechanism of acting to limit respirational water loss by shedding leaves. Make sure you're monitoring moisture levels carefully with something other than your finger. It's much more important to have an idea of what moisture conditions are deep in the pot than an inch or two below the surface, and to withhold water until the soil is nearly dry. Using a wooden dowel as a 'tell' is very effective. If you want me to post something I wrote a while back about using a 'tell', tell me and I'll hop to it.

Al