"Not sure I noticed at all before now," he admits. Maybe it just wasn't so obvious when it's static. More curious though, is what it's supposed to indicate. She doesn't seem anxious about anything, so he suspects it's not dire.

He nods in her general direction. "What's it mean? Time for an oil change?" The words tumble out of his mouth before he realizes that might have been uncouth of him. His wincing smile is an apologetic one as he waits to see if that earns him her ire.