I was playing a mixed doubles match yesterday and had a situation occur that got a little heated. In the 3rd set tie-breaker at 3 - 2 we got into a long rally with our opponents. I feel certain that we played at least 20 balls and the point was finally won when a short lob was put away by me. Anticipating the court switch I reached into my pocket to ball the extra ball out and realized that it wasnt there. It had fallen out at during the point but I am not sure when. As soon I noticed the ball one of my opponents said "I guess we when the point". I mentioned to her that she could not call a let after the point ended and she said - The point is automatically ours. We had a discussion about the rules and her partner agreed with us, that a let could be called them but it had to occur while the point was in play. I have since reviewed the rules and feel certain that I made the correct ruling - (Please point me in the right direciton if not) - But, here is my question: Since this was a recreational league match and considering the fact that she did not know the rule, should "courtesy" have been giving to my opponent such that we just replayed the point? Thoughts? Opinions?