I noticed this the other day and finally figured out it's behavior- if my PB is open and it falls asleep due to inactivity (or I force it to sleep) then the pulsing sleep light is dimmer than when I force the PB to sleep via closing the lid. Furthermore, if I force the Pb to sleep with the lid open (and get the dim light) and then close the lid, the light will become brighter.
Has anyone else noticed this? Kinda wierd, but at least I figured out how it works. I was afraid that my sleep light was like dying out or something!
Ruahrc
PS 15" Al Rev. C PB