As I said, I was aware but I completely forgot about it, and my memory only clicked when I got to report it at LAX and they kind lady asked me if I'd collected my bag there. As I wrote above, I blamed it on my own stupidity, but I also think that BA should tell its passengers.

It's true I've flown to the US before, but this was my first itinerary with a domestic connection. I never flew the ticket related to my question in the last year's thread you mentioned, as I was ill and had to cancel.