Yes, apparently she fell through something called a rift, in which she was altered and given an addition ability to the ones she already had.

[He says it matter-of-factly, but it's likely he doesn't understand it any more than Matt will. There's also the large time discrepancy and the fact that his sister is still in her own body, but that isn't really the matter at hand.]

It's tied to her temper, so I'm sure she finds it quite tedious.