Ah, thanks, in that case I guess it's anyone's guess right now as to how often the free offers are changed.
I logged into my account, then clicked on "Rewards", then on the left hand side of the screen there are a few drop-down boxes where you can select to browse rewards options by category, by amount needed, etc.
I selected the one that says Travel & Lodging, and at the top of the list that appeared was the "Free" offer.
Hope that helps!
edit - here's a screenshot

Thanks - can't ask for any better help than that! :-) Ours still doesn't have anything there - but now I'll keep watching it.