I've been seeing my T for about 2.5 years now, and I have the same problem. I sit across from her every week, but if can't call a picture of her to mind if she's not right in front of me.

She says she thinks it has to do with my background...that the whole "object constancy" think didn't really work itself out successfully for me as a kid. Makes sense, but I hope I can fix that eventually...I think I'd be a good bit happier if I did.

I will say that I've seen her twice out of context, and recognized her right away. I guess it's just the picture/connection I can't hold when she's not there.