Sounds odd - djverne (another owner) did not mention anything about the heat. Neither did user cafad from the SNAP thread.
By overheating, did the amplifier shut down or was it just very hot? Did he provide any feedback to Job or claim on the warranty then?
There was some debate on SNA about the amount of heat put out by the Job 225 (which was apparently normal). Plus, there are certain amps such as the Bel Canto ones, that do not have external (or for that matter, internal) heat sinks and they do get hot. I am aware that they are Class D while the INTegrated is Class A/B, so the operating temperatures would be different.