Thank you very much!
We only subscribed to HBO last week, between the premiere and 2nd episode of the current season. (Yes, it was due to two members of the family getting hooked on GoT and there being no other legal way to get it without waiting for at least a year. What can I say? I held out against premium programming until 2014.) Fortunately, they play the same shows and movies over and over again over the course of a week so I was able to watch the wedding feast scene in the second episode again, looking for exactly what you’ve mentioned. Lo and behold, the slight of hand was too subtle to see without the hint, but now that I know what I’m looking for the missing bead is quite obvious. I had wondered what the fallout was going to be for Sansa being honest with Olenna and Margaery. I had assumed she was going to get in trouble for it. Silly me. This is a much better outcome!
Is there a long-standing grudge between their families, or is this just to protect her granddaughter? Since Joffrey died before the marriage was consummated, I doubt Margaery gets to be queen, so it can’t be that.