Maintaining locks is perfectly fine, and many people do it. However, maintenance, when done too frequently or with improper tools/technique, can cause permanent damage to your locks.
Do not heavily maintain your locks with extreme frequency.
Do not maintain wet hair, unless you are simply twisting the roots. Wet hair is structurally weaker than dry hair, and heavy manipulating wet hair can break individual hairs. This is risky, because locks are only as strong as the hairs that make them.
Lastly, listen to your hair. If your scalp is being pulled and is uncomfortable, or your hear the sound of hairs snapping when you are maintaining your hair, stop immediately and readjust your maintenance style.
Maintenance can be done very safely with no risks, but doing it improperly can result in some of the horror stories floating around the Internet. Just be cautious, and you should be fine!