Nope, it's a recurring error. You'll see, in particular, there's one episode where the board is flashing normally for half of round 3, and then switches to the simultaneous flash about halfway through.
However, since the board is random anyway, it really doesn't pay all that much to have that extra strategy, in my opinion (Yes, I know about the whammy-counting strategy, but how many of those people on the show can actually use it with all that pressure?).
Anthony DeLegge