I get the occasional flickering in the Maze level as well (was going to open a defect on it, but wasn't sure if it was a big enough issue). To me, it only seems to happen occasionally when I'm hitting the switches and/or running into the walls trying to find my way around. Again, it wasn't really an issue to me, just the occasional flicker on the screen. But interesting that other folks have seen it as well.
Otherwise have been having a blast with it...game is fantastic..definitely worth the purchase price for those who are still on the fence about it.
*EDIT* So just went through the switch maze again, and it does flicker...and it seems to be flickering regardless of what I'm doing at the time (IE it's not in the same place each time, sometimes happens when I'm walking, sometimes when I hit the wall, etc.)
Steady 60-61 FPS...never dips, and when it flickers I still see 60-61FPS...
Again, it wasn't enough to distract me, but it's definitely there...for the record I haven't seen it anywhere else.
Reported in Mantis, just for tracking purposes.