Yes - this is normal and expected behaviour.
Many of our DJ products utilise "Touch-Capacitive" platters. Touch capacitive technology is designed to allow for touch-based interaction with devices.
It works through utilising sensors that detect changes in capacitance. Capacitance is the ability of an object to store an electrical charge.
When you touch the platter, your body acts as a capacitor and the sensor detects the change in capacitance caused by your hand's proximity. This change is what causes the platter to stop.
However, everyone's bodies are different and will have varying levels of capacitance. It is also possible for capacitance to be detected over small distances. Because of this, you may find that holding your hand above the platter causes it to register a touch. The distance in which this occurs will vary from person to person.
To avoid unintentional triggering of touch capacitive platters, it's important to be aware of your hand's proximity to the platter and to adjust your movements accordingly.