I got my D3 today. I LOVE this phone! So far, it has been almost flawless in operation with a few exceptions.
Sometimes, I can't close browser windows from the browser window list. Instead, clicking on the "close" icon on the right hand side of the list, it just opens that window. Leaving the browser and coming back to it seems to fix it sometimes.
Looking at it again today, it seems that maybe the "close" icon is just very picky, like you have to tap it right on the circle or it won't close it. I'm not entirely convinced, but that might be what's happening.
Yeah this is also on the Droid 2 as well, it's normal. You have to hit the close icon exactly, or else you'll go back to that window. I just used a Droid 3 at the Verizon store and it has the same functionality (unfortunately).