Before racking at 1.010, I would have stirred it well to mix the yeast back into suspension, that yeast was most likely not dead, just buried by the lees, (For Example: When making a 2nd run wine, the pressed grapes start to ferment again right away without adding any more yeast to the must).
There is a good chance that the yeast wasn't dead, what was the temp of the wine? Sometimes we overlook that important part of fermentation, too cool and the yeast goes dormant.
What was the starting SG?
Depending on the starting and end SG, plus the alcohol tolerance of the yeast, the yeast might have reached its alcohol tolerance, and started to drop sediment.
If the wine has a noticeable separation of wine at the top and heavier lees\sediment on the bottom, this is natural - Once fermentation is finished and not producing any CO2 that would keep the fruit floating on top of the wine, the sediment\lees will drop out of suspension.
The fact that the airlock was still active doesn't necessarily mean that it was still fermenting, it could be the gasses escaping. If in fact it is done fermenting at 1.010, a few nutrient additions could have kept it fermenting longer.
I hope that this helped a little.