"Resuming Windows" indicates that the computer was in hibernate mode. However, if you shut it down properly, it would be virtually impossible for it to hibernate.
I do know that if you don't customize your power settings and then put your computer to sleep, Windows will hibernate after a certain period (default settings, I always change them). But since you said you shut it down, that doesn't seem likely.
Try replicating the result: shut it down, leave it for a little while, then boot. See what happens. It could have been a fluke, you could have accidentally clicked the wrong button (not likely, but still possible), there are many possibilities. But try recreating what happened, and we'll analyze what we get.
I know it's weird at first getting used to a new OS, but once you get familiar with it, it's awesome.
Some things in Windows 7 can seem quirky at first, and take some getting used to. But your particular issue seems to be isolated to your computer (or that single shutdown instance). I have never seen this happen before.
See if it happens again, and let me know.