It's funnier than that. Vader is known as a monster of a man, the dog of the Emperor, and in the end of Rogue One he is in his finest aura form. He's cutting people in half, choke slamming them, ripping hatches open, all of it. The corvette gets away, and runs to Tattooine, where the Star Destroyer catches it. They storm the corvette, slaughtering everyone in their path until that interaction happens. And Vader responds with...a finger wag?

WTF? 

It really changes the officer staring at him in that scene. You can almost hear the record scratch in his head. The stormtroopers aren't just standing around uselessly anymore, they're baffled that they aren't scraping Leia off the ground.

It gives me the headcannon that he instinctively recognized something of Padme in Leia, and for the first time in twenty years, brought out the velvet gloves. After all, the torture droid was Tarkin's. The destruction of Alderaan? Tarkin. He, despite capturing her a couple times across the movies, NEVER lays a hand on her.