Yes, but at Keller's restaurant it's not charged in advance -- it's just a "gratuity included" situation. The specific definition in the FLSA states that tips for an employee are "actually received by the employee", which is the main issue in counting prior ticket purchase as gratuity.

Also, Nick, if you're still reading -- do you think that the prepurchase model materially affects people's spending on e.g. upgrades and drinks? My wife and I did Alinea & Aviary on November, and I was definitely happier to spend a little more given that the original "purchase" was so many paychecks in the past.