Certified GKH Gardening Expert
Yes, yellowing leaves can be a sign of overwatering. Often the leaves will begin dropping soon after they turn yellow. For now, stop watering to let the plant recover. Then begin again with less frequent and/or smaller volumes of water at each watering.
Here is some information on overwatering. Underwatering can cause some of the same problems, such as wilting, but you will eventually be able to tell the difference.