I had my first gig with the X32 yesterday. When packing up, I found the S16 felt rather warm, especially on the part of the case above the power switch (power supply?) - I'd estimate somewhat above 50°C (120F), since it felt hot, but not yet painful even after leaving the hand on it for a while.
The S16 is mounted in black plastic 10U rack case, with a 1U vent above it and plenty of air below (a 4U opening). The back of the case, which was visible from the audience, was closed. The rack case sat at the front of the stage in the sun. The inside of the case didn't feel as hot as the S16. Our X32 Rack was at the back of the stage in the shade and remained cool.
The handbook doesn't mention operating temperature specs for the S16. Should I worry? Spray-paint the rack case silver? Reconfigure the rack? (There's a 4-channel digital amplifier in the second slot from the bottom, which remained cool.)