"your days are numbered" could mean any number of things from "I'm going to kill you" (highly unlikely from a little old lady) to "we will oust you from your position" to "some day you won't be around any more". Unless she was brandishing a weapon, I don't see it as a threat.
Well according to Clinton-speak any word can mean anything you want. "your days are numbered" is a classic statement and we all know what it means. Whether she meant it or not I can't say since I can't get inside her head. She was clearly nuts.