of a girl I knew in high school. Becky and I shared one art class in all our years of schooling, and we hung in different circles, so while we were friendly, I'm not sure I'd go so far as to say we were "friends". She was nice enough, and we had fun during that art class. We exchanged Christmas cards from high school till probably about the time we both hit our early 30s, and that was the ONLY communication between us. I stopped sending a card first, then she stopped a couple years later. I have *no* idea why I got one this past Christmas; there was no "big" news to share, just the usual update. What I think happened was Becky put her husband (whose name I don't even know!) in charge of the Christmas cards this year, and he must've found some old list and just sent a card and newsletter to everyone on it.
Yes, the Big Bang Theory book devotes a chapter to the birth of Young Sheldon and also occasionally references the show throughout other chapters. A few things you may or may not have known: the actor who played George Cooper on YS previously guest-starred on BBT as one of Leonard's childhood bullies who now wanted Leonard's help with an idea of his (a ridiculous one, IIRC--it was one of the episodes I usually skip in reruns). Also, the writers had to somewhat retcon George in YS as Sheldon and Mary always bad-mouthed him in BBT. Since Sheldon supposedly has an eidetic memory, the retcon really didn't work for me but I understand that it's just a TV show, and when they were writing all those episodes of BBT, they weren't thinking of a spinoff and weren't prepared for how popular George was with fans in YS.
And I'm sure you know the actress who played Mary in YS is the daughter of Laurie Metcalf, who played Mary in BBT, which is why she bears a strong resemblance to the actress and why she nailed so many of Mary's mannerisms 😁