Computer turns off, but turns itsself back on?

I am running Vista Home Prem, Dell Inspiron 1501 Notebook. I shut it down, and then I store it in my case. Somewhere during my trip home, the computer turns itsself on, because when I retrieve it from my case...it is warm, the red battery indicator is blinking, and it is active. When I open the Lid, it tells me Windows recovered from a shutdown.

So is it just my laptop doing it, or are others doing this also? I know how to shut it down properly, before I close the Lid every indicator light is turned off, to enclude the Wifi.