5 Month old MBP not working properly ?

We bought our 2.4 Ghz aluminum MBP back in either June or July (don't remember which) and up until now, everything has been working fine. I do have Apple Care, so I'm not worried about a replacement or fixing it should it come to that. What does trouble me is why (unless there's a good explanation) after only 5 months, a $2000+ laptop should display signs of trouble. Here's what is happening:

Last night, I pressed the power button (as I usually do in order to initiate a shut down) and chose "shut down". I then closed the lid and walked away. Five minutes later, my wife tells me that the light on the MBP is still on, which seemed strange, but t'was true. I opened the lid and the light went off, closed it, and it went on again, but there was no other type of activity ... aside from hearing the hard drive still being on. It was almost like it was asleep, but without the ability to do anything.

I left it alone, thinking it would just shut off, but apparently not because this morning when I went to turn it on, the battery was completely drained. Now, at the very least, when one shuts the lid on their laptop, it should go to sleep. I have my preferences set for optimal performance w/battery operation, so it's a no brainer. But this is not what happened. Something caused the MB to stay on, while the lid was closed. I didn't have any running programs in the background, either.

I'm very confused about this behavior, and was wondering if anyone has gone through anything similar with their MB's ? And one last question: Should it come to Apple replacing this MBP, what is the likelihood that I will be able to trade it in for the newest model ?

Doug

That does not sound like a hardware error. It sounds like a software problem.
For what ever reason, your laptop did not go to sleep. Perhaps a program was running in the background that would not suspend. Various applications can cause this very same effect.

I run into this a lot with windows machines and have seen it some on macs as well. Transmission is a notorious app for not letting my mac go to sleep when I close the lid.

I doubt if you will need a replacement mac, and as far as I know Apple will not upgrade you to a newer mac, unless you have a history of the same problem over and over and over.

Well, as I said earlier, there were no programs running in the background or otherwise. I always quit all apps before shutting down, and this time was no exception. Any other suggestions ?