PP here. If she does know and hasn't said thank you, I agree that it's a bit off. But I think it's much more likely that DB presented them as his gift. At most, he may have said that you took the pictures, but I bet he didn't say it was your idea, you actually developed the pictures yourself, bought the frames, etc. Then she might be thinking that he liked a pic you snapped and did the rest himself; I'd still tell you I love the picture, but it's less weird in that context if she doesn't.