Upload & Sell: Off
Some ppl just like to have their picture taken, though it would seem they would have put yours up on their FB page. I take it that they put this new session's shots on their FB page. If so, that is interesting and would indicate they like these and didn't care so much for yours -- not saying your shoot was bad, but sometimes people are funny about what they like and don't like.
If you're shooting their wedding, I would talk to them about it before the wedding to help ensure you deliver pictures that they're happy with.
I had something similar to this last year. Shot this session with a couple, got very lukewarm feedback on the pictures. I decided to ask them what the issue was. Turns out the girl *hated* her side profile. She hated it so much that she literally did not like a single picture of her face turned to the side. She was borderline neurotic about this.
I did another session with them for free. I had the girl look directly into the camera for every single picture. She loved the pictures.