Just wanted to say, I feel you. Sometimes people here come across as real sticklers. I understand your frustration and yes, it does seem like BA could have accommodated you without too much bother to themselves. Rules is rules, however, and these are the risks we run when booking separate tickets. As others have said, just be glad that the change didn't go the other way and you're not missing the connection instead.

You're hardly spitting the dummy over this, just venting. Nothing wrong with that.