Several different issues can cause a few drops of water to drop from your bathtub spout. If your spout has a diverter, the water drops are perfectly normal. A small amount of water is allowed to bypass the diverter so that the diverter will reset. This allows the water to come from the tub spout instead of the shower head the next time the shower is used. If the amount of water coming from the tub spout affects the water volume of the shower head, it probably needs to be replaced.
The drip could also be caused by a worn washer in the shower faucet. This is probably the case if the drip continues all day. If the drips stop after about an hour, it is most likely water draining from the shower head.