No Proclamation or other official notice on Whitehouse.gov. Not on Whitehouse.com, either!
The only place I saw anything indicating the flag should be at half mast are AFP and Huffington Post, neither of which I find particularly persuasive.
In the mean time, there is still nothing on the White House website of any of my other usual sources of information.
BTW, remember to fly your flag at half-mast tomorrow in rememberance of Pearl Harbor Day.