Don't stress or worry. Unless it gets high temps. Heat is an enemy of Li-Ion and similar. They do not suffer "memory effect" that other do. Meaning you don't have to worry about partial charges. It is recommended to periodically do a full discharge. Before anyone says that is bad you can't do a real full discharge the battery won't let you. But do down to what the phone lets you to keep the battery from atrophy maybe once a month. That is for anyone not just docks.
If you want to learn about batts, Google BatteryU.