Seems like this is the second week in a row that the Sunday redeem riddle has been late. No official explanation from what I can tell.
I also have had a late Taptitude Tuesday redeem code in the past as well.
You'd think these are things that should be automated, but from the looks of it, the FourBros manually do the update and sometimes Real Life™ can get in the way.
UPDATE: Monday is almost over and still no riddle. Tomorrow is Taptitude Tuesday, it will be interesting if they post the Tuesday code to Facebook or not.
UPDATE 2: Tuesday is now almost over, and there is no sign of Sundays riddle, and now the Tuesday's Facebook code is AWOL as well. A lot of comments and concerns on Facebook, but no official response has been made. Hopefully everything is ok with the FourBros.
UPDATE 3: Late Friday, still nothing on Sunday riddles. The Tuesday code is did show up: facebook82713
UPDATE 4: Sunday's over and now two Sunday riddles are AWOL. Things aren't looking good.
Someone mentioned the Four Bros might be on vacation, but I doubt that. They have announced vacations in the past, so the silence on this pretty much means that something is not right. What it is, we won't know until they come back. I pretty much expect it to be Real Life™ based though.