If a tip wasn't discussed in advance, and was demanded when I arrived or after the session, then I would complain about it. If the experience was stellar, then I would not be overly upset. Since this was up front, I probably wouldn't post a complaint since any other punters would likely also know up front.
I would probably pass on the session though. If tips are being discussed before the appointment, then the menu is probably ala carte, and there might be a lot of clock-watching and complaining. Chances are it would cost a lot more than expected initially.
It could have been a typo, but if it was text messages, less likely. I make typos in a PC often and they are often grammatically correct - muscle memory and all. Typos on a phone? That doesn't happen to me, but I use text a lot less than email.