As a provider, I don't see anything wrong with that.  If I had established a good relationship with a client who had a solid understanding of the exact nature and boundaries of our relationship, I'd be more than happy to send a photo. Especially a non-nude one.  One of my friends has taken many photos of me himself, actually -- some of which ended up on my website!

and by "regular", I mean you've seen her at least once a month for the past 6 months, at least. Then it would probably flatter her, especialy if you put it the way you did in your post. It sounds endearing and sweet.

But if you've only seen her once or twice it might seem creepy.