Display Behavior on plug in and out question

[volsav]

New phone purchased 8/8/10 with Android 2.1:
Android 2.1: plug in: display shows unlock screen, plug out: display shows unlock screen
Android 2.2 pushed to phone about 9/10/10:
Android 2.2: plug in: display shows unlock screen, plug out: display: display gray, meaning dimmly lit. Not black like when asleep.

Is this normal Display Behavior?