It was way back in 2007 when Debbie mentioned in the comments that Elsie Tanner’s maiden name was Grimshaw. I always thought it was odd that particular piece of information just sat there on the shelf, not being used. You had a woman named Grimshaw living in the same house that a woman named Grimshaw also once lived. I thought it was obvious that she simply has to be related to Elsie. And now, finally, the writers have decided to make that little piece of information official.
Will it have a big impact on any future plots? Not really, I imagine but I do like it when the show takes its own trivia and continuity and actually does something with it.