
I can't confirm a forum source, obviously, but it is being reported more or less everywhere else so why not. It just so happens that I have modified the chassis of an older Xbox 360 console to improve air-flow and ventilation before.
Combining Arctic Silver 5 thermal paste on CPU and GPU, a modified fan shroud to force more air "through" the heatsinks to escape the chassis, cutting away some of the mesh of the inner shell and laying the console horizontally instead of vertically makes two noticeable differences; the fans always stay on low speed and noticeably more heat is exhausted from the rear of the console.
Still, you shouldn't have to open an Xbox 360 console to make sure it's properly ventilated anyway, so let's hope that warnings such as the one displayed above are not common.