Half-mast?

The local wingnut jeweler I pass a lot that has their DON'T TREAD ON ME flag up?  Yesterday, there was no Old Glory and the DTOM flag was at half-mast.  I googled frantically, trying to ascertain why, exactly. Obama's birthday isn't until 8/4.  Civil war ended in April.  I did find Orly Taitz's web site, so that was fun/scary.