I'm sure they had given it prior consideration. But I don't think they'd anticipated NAB's announcement. I suspect if NAB had announced a 10bps move (or 15 or 20 or whatever) then ANZ and WBC would both have announced theirs by now.
If I were them, I'd be weighing up whether this gives them the opportunity to grab more than they would've otherwise since any the bulk of the poor publicity has already been worn by NAB.
If I were them, I'd also be tossing up whether there's a competitive advantage in seeing how the other now reacts. You can then position yourself exactly where you want in terms of a competitive position.
My broker reckons they big 4 all end up around the same mark eventually, and given that Westpac and ANZ were higher than the NAB and CBA, they should be able to come up with a drop of at least 15 points I would have thought. Its the same reasoning as to why the NAB and CBA did not drop much as they were already low in the marketplace.
Big Rog