Hold the presses! Kristen Stewart actually looked happy. The infamously sulky “Twilight” star was unusually chatty Sunday at Skintimate’s Gersh Agency brunch celebrating her flick “The Runways.”

“Everyone ... was surprised to see her in such an upbeat mood,” an eyewitness told us.

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Not so happy at the brunch? Justin Bartha (“The Hangover”), who showed up late to the Greenhouse Actors Lodge, was annoyed to learn he missed the buffet.

“[He] threw a fit and stormed out,” the spy dished. 

"The Runaways" stars Kristen Stewart, left, and Dakota Fanning (Getty)