Well I guess I've learned my lesson about clicking on the rate details. But honestly, I've reserved about 650 nights in Marriotts and have never clicked on it except in the unusual case of a local promotion ("Stay, Shop & Dine" etc.), and I've never had anything similar sprung on me. The rate, cancellation window, and any deposit have always been clearly listed before the final booking step, without having to click on "rate details".

I'm not planning on canceling within the 21-day period, so I won't be out any money. I just hate to let Marriott have that money for the next 8 months! But we're now on day 11 and no deposit has hit the credit card, so it might be a moot point.