First thing first, do check if you've removed the plastic films on both sides of the silica gel thermal pad in order for it to effectively directing the heat generated by the SSD while in operation onto the aluminum casing and get dissipated from there. The design of our enclosure is that the aluminum casing would work as the heatsink for the NVMe SSD enclosure. Therefore, it is going to get pretty warm to the touch when the SSD is in use (even after it is used. It will need some time to get cooled off). Do handle with care.
Secondly, most SSDs are rated for running within a temperature range of 0ºC up to a max temp of 70ºC (32ºF to 158ºF). So, it is normal that the whole enclosure gets warm when it's in operation.
Lastly, if you're wondering if there's any way to enhance the heat dissipation. You may consider having the SSD enclosure to be placed on a laptop cooling pad, that helps circulate the air around it. That would certainly help. Also, placing it in a less compact & open space would help too.