There was a lot of talk for a while about Young Sheldon rewriting the story laid out in The Big Bang Theory - that George was being a loving and devoted husband rather than the cheating husband Sheldon once described. I don't like when writers of prequels retcon an established "fact," so when George hadn't had the affair we were all expecting and became ever more unbelievable that he would do so this season, I was becoming disappointed that such a huge milestone event would go unaddressed. Sheldon's knocking three times was so integral to The Big Bang Theory, that not seeing its origin story play out would be a great let down. So the fact that they kept that origin story while finding a way to make it true to Sheldon's telling of it AND being true to George's character development was VERY IMPRESSIVE! We've accepted a man's account of his (roughly) 20 year old memory as infallible truth... A man who doesn't understand sarcasm, politeness, empathy, boundaries, etc. This episode perfect played out Sheldon's memory while acknowledging Sheldon rarely "gets it." He's book smart, but not people smart. The writers showed ingenuity in providing depth to a story we've waited years to actually see play out.