Bet it's a scam.... at the bottom of her backpage ad is a web address...
http://www.massagesbymegan.com/
To book an appointment you have to prepay $5.00, low enough to not set off alarms but enough to make a decent living if she gets enough suckers to sign up. Also states on "her" page that if you don't think she would work for you links to others..
I'd pass.