I would agree with this. I've done IR tests on the Standard setting (50 contrast/50 brightness) and the quick onset IR happens on my 60ST50 just as fast from the DVR and TV menus as it does with my Custom (82/56) setting. (And, again, it's visible on normal material, but only for a minute or two.) Never saw anything like it on my old plasma.
And for those who might charge that I'm careless or whatever, I am totally babying this set. Besides, the quick onset IR is something that happens pretty much immediately, with the menus up for less than a minute. This isn't a static-logo-up-for-hours situation, although that can be an issue too. I'm pretty sure I have over 400 hours on the set at this point.
Is it possible that altitude or other environmental factors could be aggravating this? Could explain (beyond panel variations) why some of us are seeing it and others aren't. I'm around 6000 feet up. No buzzing, but I do have this temporary IR!