The real question being, does that mean he has to keep his distance from his mom and brothers (since predatory birds usually eat mice)? :)
I was saying she would be startled because she wouldn't have seen him coming. Since she's in an area is thinks of as safe and she doesn't think any other students are out yet, she would set her internal clock and then ignore the rest of the world while she deals with herself. When she lets her guard down like that, anybody would be startling. From your average-looking Garen who offers a friendly greeting to a guy putting a bag over her head. After the first startle, she would calm down a little if was Garen, then calm down some more when she sees he's a Faunus. But when she's in the kind of state I'm thinking of for her early morning practice, she would have absolutely no idea if anyone or anything is around until it makes its presence known.