Typically, using a finger to test for moisture if your pot is deeper than 5" results in over-watering. This is because when the top 2" of soil is dry in a 10" pot, the bottom 6" can still be100% saturated, though I wouldn't expect that to affect the newest foliage first.
One thing I did think of after I left my first post is, I have seen some species of ficus do some wholesale shedding if I bring them in from outdoors when central heating is already in operation - a humidity issue. Any chance the plant has been subjected to that type of change? This would be especially true if the plant is now sited near a heat vent.
Al
