Luna tilted her head as she took note of Hermione's flushed look. She may be a bit of a quiet girl, but Luna always considered herself very observant. She could tell when people had hidden emotions. She was also very observant of physical appearances, well physical appearances of people she thought attractive, so she was sure that nothing looked wrong with Hermione. But if the girl said there was, she believed her.
"Not something you can see?" Luna closed her copy of the Quibbler, Hermione now having her full interest. "Do you have green patches of skin? Because there's been a recent surge of a rare breed of lancewig flies going around and they can cause color changes in the skin when bitten. There was a whole article about it in last month's Quibbler. I can get you a copy. If you want."
At Hermione's question, she paused. Lancewig flies didn't cause problems with anatomy. So her idea for that was thrown out the window. "I know it pretty well." she answered.