 What had given it away to Don that the attractive redhead he saw on the train was not actually a natural redhead?
The object loomed out of a cloudbank at twelve thousand feet and Studley changed course to avoid it. Don Cort had been dozing in what passed for the club car on the Buckeye Cannonball when the train braked to a stop. When Don had entered the club car he'd seen her hatless head from above and noticed that the hair along the part was dark. Don hesitated, shrugged at the redhead, said, "Excuse me," and followed the conductor. Don made his way up to the locomotive and found a bigger knot of people gathered in front of the cowcatcher.
 Her dark roots were showing.
 Her skin tone was too off to match the hair color.  The red tone of her hair was far too bright to be considered natural.  She was carrying box hair dye.  Her dark roots were showing.