White Watermelon?

Well friends, the elation and joy of successfully growing my first large watermelon was quickly deflated when I opened it to find it wasn't quite ready - at least I think that's what this means (see image below). I've searched every resource possible and I can only find one picture of a white interior of a melon and it's a honeydew.  Definitely not what this is! 

I planted my watermelons from seedlings on Mother's Day of this year (May 8, 2011).  When trying to figure out where I went wrong I found this article very helpful for future reference; Harvesting Melons: How do you know when a melon is ripe? - , as well as this one How to harvest garden Watermelon.   (Actually I truly NEVER knew after three seasons of attempts that it's actually better to "cut" the watermelon off the vine.  I was doing the "slip" method).   Using this last resource, if I count the number of days it's only been 66, so I'm shy of the 80 by approximately two weeks. (Unless I count time from seed to seedling by guessing what happened to them before I got them.)  I have several more growing, so I'll assess the ripeness again in two weeks or so using my new information I resourced. 

Of course I'll share the results, and would love to hear about your watermelon experience!