Brand new nMP needs four-finger salute...

I received my QC stock nMP two days ago, but already ran into a nagging problem: the attached Thunderbolt Display would go into some sort of sleep mode (not black, but dark grey) and could not be roused from it. The nMP itself kept on working fine: I could SSH into it from another computer, Time Machine worked normally, as did video streaming to my ATV.

AppleCare suggested resetting SMC and PRAM, and that solved the problem for now. I'm left with the question of why this was necessary on a brand new computer?

Two days later the problem hasn't reappeared, so resetting SMC and PRAM seems to be the solution to an unresponsive Thunderbolt Display.