The bottom of the ECLIPSE gets warm during hot infusion sessions. Is that normal?

Yes, when brewing with hot water, you may feel the Bottom Cap get a little bit warm and that is normal. Similarly, the bottom of the ECLIPSE may also get chilly for cold brews. This is because the bottom of the ECLIPSE is detachable for thorough and easy cleaning, and the threaded parts transfer heat more easily (similar to how the neck of other insulated bottles may get warm or cold, depending on the temperature of its contents.)