The anger in his eyes and voice, as well as how his body was completely tense, told Mara something very bad had happened. But considering he was uninjured, from what she could see anyway, it wasn't something physical that had gotten him all riled up in anger. But it only served to make her that much more wary. Anger to the extent Galen was feeling it currently was very dangerous, and Mara would do whatever she could to bring him out of it. Even if she needed to use Force abilities against him to do so.
Mara noted his hand twitch slightly towards his lightsaber, but hers remained still and at her sides. She made no move that would make him think she'd draw her weapon on him. No, if there was going to be any drawing of weapons, Galen would be the one to initiate it. Mara had faith in her abilities that she'd be able to dodge and draw her own weapons quick enough to counter any charge he'd throw at her.
"What are you busy with, Galen? What mission are you on? I don't remember there being an attack upon this city currently." Perhaps if she could discern where he was going to vent his anger, she would be able to piece together what had originally upset him. Though that didn't always work, but it was the truth 8 times out of 10, more or less. So she would try to discover what would be getting the focus of anger and work backwards from that.