Brotherman, believe me tips of that magnitude aren't uncommon in this industry. It was just a misunderstanding, the customer service at SRM is top notch. I've literally walked out and stiffed a girl by 20 bucks(unintentionally, it was a long ass day, i just wanted to unwind) without being chased down, i just made sure next time i saw her i paid up front, left her a lil tip, and apologized. Unless one of these girls really goes out of their way to make my session hell, i'll leave an extra 20 on top, its courteous.
I sincerely hope you didn't make a scene about it, because that will stick with you. Just like servers, Mpa's remember the douche bag, cheapskates and good tippers. Throw on a skimpy outfit and heels for 12 hours in winter and see how pissed off you get when you get stiffed by a client.
Go back with the same attendant, and don't leave a tip., but don't be a dick and stiff her on purpose. At the end of the day, its 40 bucks man, the room price for 30minutes, its not the end of the world.