lhbsurf - We had the same experience at Sublime. I added an additional 5% to the S/C and the waiter said to me "Is that all you are going to tip". Yes, very uncomfortable. We haven't been back. Makes me wonder if the owner is aware that he/she is losing repeat business.
My response to that would be, "Yes, because 15% has already been added." If they argue, I'm done, and won't return.