Agreed but when did the “under maintenance” websites come up? That in itself would be enough to be considered a notice unless the website was down, blacked out with no landing page, for many hours and the “under maintenance” just appeared recently which then, yeah looks a bit suspicious and worrisome. But then it could be simply a case of “oops, I forgot to set the redirect” thing and not necessarily a malicious attack.
OK, I used up my daily quota of optimism here 
Let’s hope we’ll see some actual explanation soon.