River caught a glimpse of the coins in his hand before he closed his hand around them. Mostly all she'd seen was the glint of gold. But as he responded, she came to a stop, noticing his caution. She couldn't not, she'd been around the universe enough to learn how to read body language of various races. Looking at him it was hard for her to put an age to him, but he was definitely old enough to be able to take care of himself. Now, if he was displaced from his own reality or not was the question. It was hard to tell without more conversation if he was a native and she just hadn't seen him before, or if he had been brought here by the Seal.
Smiling warmly at him, River kept her presence unintimidating. Oh she knew she could have an intimidating and imposing presence when she wanted to, but right now, she was wanting to be friendly. "Yes, it is. Just out for a little walk and to enjoy a little breakfast. How about yourself?" She wasn't going to just jump into the whole Seal business without him giving some clue that he needed to hear that particular information. It wouldn't exactly be good if she started in on that talk to find out he was merely an unsuspecting native to this place. He'd think her mad in that case.
Well, even if he had been brought here by the Seal, he'd probably still think she was mad. Most people had the same reaction to those who gave them that explanation. Unless of course they were used to war, then it was more adjusting to the new surroundings and the circumstances of this war. And well, River Song was a little bit mad anyway, but she preferred herself that way. One needed to be a little mad to travel with the Doctor through time and space.