Email Opt-In at Hotwire.com: No Means Maybe?

I recently booked a flight on Hotwire.com. Overall, the process was impressively user friendly. But there was one thing that kind of irked me: the way they handled their email opt in.
It started when I was entering my contact information. Upon landing on this page, the box beside "Yes! I want to hear about great deals..." was pre-checked, as shown below:

Not wanting to subscribe, I quite deliberately unchecked the box, figuring that would be the end of it.
I went ahead and booked my flight, then a bit later, I received this email:

I was quite alarmed for a moment, wondering whether I actually had forgotten something (and whether it would affect my booking). It was only upon reading the body text that I realized they were again asking me whether I wanted to subscribe to their email list... even though I had specifically indicated just moments earlier that I did not want to.
If the box in the contact information section had not been checked by default, then perhaps this would be okay. (It's just possible that I did in fact want to subscribe to their newsletter, but just neglected to check the opt-in box.)
But that's not what happened here. I didn't "forget" anything. I quite deliberately unchecked the box. The meaning is clear: I don't want your emails!
I found this both annoying and confusing. When it comes to email subscriptions, a clear no does not mean maybe.

Actually, for the most part I was very impressed with the website. That's why this one issue really stood out: it seemed inconsistent with what was otherwise a very positive user experience.
The extra email acts as a "sales" landing page for their email list and may persuade a few extra people to actually subscribe despite saying no the first time. They maximize their efforts this way resulting in extra $$$ down the line.