What was Big Willy Shakes going for?
For all of this to make sense, we first have to know that Queen Margaret's late husband was bumped off the throne by Richard's family so that Edward IV could be crowned king. Plus, Richard also killed her son, so she's pretty unhappy about that.
Oh, and did we mention that since Margaret is a woman and a widow, her livelihood depends on the people who murdered her husband and son? In other words, Margaret was once a queen but now she's a charity case without a husband or a son...and she's angry about it.
The grief she feels is awful, and the fact that the murders have gone unavenged adds insult to injury. More than anything, Margaret feels irrelevant, and her unnoticed misery only fuels her wrath.
Hastings says what pretty much everyone else is thinking: this chick freaks me out. And with good reason. He's scared because Margaret is no sissy. She's done some pretty nasty things in her day. Back in Henry VI, Part III, she taunted Richard's dad by putting a paper crown on his head and waving a bloody handkerchief in his face. By the way, the handkerchief was dipped in his son Rutland's blood. Ick.
At first, most people (especially Richard) dismiss Margaret's cursing as the grumblings of a "hateful, bitter hag" (1.3.16). Most of the other characters think she's insignificant, too. Their first reaction is, "What? You're still here?"
But then Margaret's curses start to come true. Creepy, right? So if Hastings thought she was eerie in this scene, just wait until the end. His hair will really stand on end when he sees everything she's right about. Yep, Richard will have arranged his funeral by then. Too bad he didn't listen to Margaret.
Shakespeare seems to like this idea of hair standing up. In Henry VI, Part II, Winchester says, "comb down his hair; look, look! It stands upright!" (3.3.15). After he wrote Richard III he used it again when the Ghost in Hamlet says that the secrets he knows would make his son's "hair to stand on end" (1.5.19).