Angry? Oh no. Is it because of something she said? He does look a bit displeased. She better try to fix this before it gets worse.

"Er..." she begins concernedly, "Is it something I can help with? I hope I didn't say anything too rude..." She decides that saying she's human was a pretty bad idea; it's not like it's obvious or anything. What if he thinks his intelligence has been insulted? She feels a vague sense of disappointment with herself for being so careless.