Sister In Law Help

Last year, my sister-in-law called my wife to ask her to send me over because her electrics were out. My wife asked me to go and didn't want to come with me so I went alone. Sister-in-law is 32, slim, small boobed like my wife and a teacher in a high school. She lives about 45 minutes away so I went over and found a breaker had tripped, which I reset . A quick look over to make sure that nothing was obviously amiss and said that I would leave . She persuaded me to stop for a coffee and within 10 minutes she had my cock in her mouth. She took the lot and swallowed, something that my wife won't do. By the time that I got home she had called my wife to say that all was OK and to thank me again. Now, I don't know if it was a set up of some kind but I've never mentioned it and it hasn't happened again. I'll just count my blessings and leave it.