I know. Hence extreme slight suspicion.
But for the most part, we can all agree that Apple really doesn't give a flying ---- (fill in the blanks) about Black Friday.
Also as a note, the 2012 MacBook Pros and MacBook Airs released on a Monday (6/11/12), so I wouldn't be shocked to see the 21.5" iMac release on Friday, November 30th, the last day of the month.
Yes I do realize every iMac prior was released on a Tuesday, but I think these days all patterns and past release dates have been thrown out the window.
Every exception you've seen to Tuesdays for Mac launches has been due to a simultaneous keynote event. You certainly can't rule anything out, but I think I'd assign 91% probability to Tuesday Nov 27 and the remaining 9% split among the other 9 days.