It does seem weird that she's commenting on a photo, without actually saying anything about the photo, but rather announcing her own thing. To me that suggests she doesn't know the right way to do what she wants in Facebook, or isn't careful about doing so. It does give the vibe of "taking every opportunity to toot her own horn," but that may just be accidental if she's mistakenly posting the wrong way.
The thing that would annoy me is that it seems like she's trying to get in touch with him, but is using Facebook when he's rarely on it--like she is expecting you to relay messages to him. I wouldn't want to set that precedent. I would probably say ONCE, "Hey SO, Carla posted on my wall and seemed to be talking to you. Can you contact her and let her know a better way to reach you?" Or, with SO's permission, I would pass on more reliable contact info to Carla, and if she continued to contact me (wanting him) I would say, "I dunno, have you emailed him?" or whatever.