As is the case with most electronic devices, it is expected to observe that the aluminum shell of the USB-C hub gets warmer, particularly if the USB-C passthrough charging and/or all ports on the hub are utilized. 

Internal testing has measured and validated operating temperatures of up to 125°F with our USB-C hubs, which is well below the maximum rated temperature of various integrated chipsets (IC) in our USB-C hub of 212°F.

In summary, please note that heat is not an indication of an issue or defect with the USB-C hub.

For additional information please see our article about Understanding Heat Generation in Electronics.