This is something I see all the time when I'm doing mechanical surveys (in other words, when working without an electrician to open doors). Always keep your eyes open. A quick scan around the room can reveal issues you didn't set out to find. I agree that the pipe is probably reflecting heat from another source, as is the latch on the upper right side; however, the heat on the face of the panel suggests radiant heat from a source inside the panel. This type of panel tends to have contactors, overloads and other heat generating equipment inside, but look where the heat is concentrated... around the switch. This would be a worthwhile scan.
I've attempted to attach a recent image I took of a disconnect switch... showing the image that prompted me to have the switch opened and the results found inside.
Best regards,
Thomas Kremser, Altheus Infrared, Inc.
www.AltheusIR.com
