I vote that it's a bit weird, but I would ignore it (unless people start responding and having whole conversations on your photo, as one poster mentioned). It sounds like the person doesn't quite understand Facebook, and that they're actually posting on your wall. Even if your BF can see it, that's not the correct place to post messages for him.
I had something similar happen once, and assume the person didn't understand that they were commenting on my wall rather than their friend's wall. I posted a photo from a party at my house. Several of my friends in the photo, including "Sue," were tagged, which allowed their friends to see the photo. (Completely fine by me.) Sue has a friend "John," whose name I vaguely recognized, but I've never met John nor communicated with him in any way. I wouldn't know John if I passed him on the street. John commented on the photo, "Looks like it was a great time! Wish I could have made it!" Um, I don't know you. Why are you making comments that make it sound as though you were invited to, but missed, my party? It was odd, and I can only assume that he thought the photo was at a party that Sue was throwing.