Yes, it’s normal, and it happens to all electronic devices. However, it’s always best to place your terminal in a well ventilated and accessible spot. Also, don’t put anything on top of your equipment, and avoid placing it on top of another device that also creates heat, like your audio receiver.
Lastly, enabling power saver mode (found in the Helix TV terminal’s Settings > Device Settings > Power) can give your terminal a little break and allow it to cool down.