I've never heard anyone comment on it. Unless someone has seen the carving on the rail, they would probably not know the significance anyway.
Would love to know what everyone thinks about the way David answered when Victoria asked about his wife. He said something like, 'she's no longer with us.' Just because she's not with you, doesn't necessarily mean she's not with someone else;) I just got the feeling like she's not dead and may come back at some point. I've been wondering about her for a while, actually.