Woops, you are right :). Just saw the in-game window mentioning it. I need to pay more attention, have you always been displaying a notice in the window there during maintenance / patches, or is that a more recent thing.
Still think there needs to be a change of wording in "The version of your client is not compatible with the matchmaking server. Please update your client and try again". The problem is that people think there's something wrong with their game when they don't get the option to immediately update, they then may uninstall / re-install the game to try resolve the "non-issue",