Under the Light Effect section of the manual, you are able to adjust that light so that it's on or off. It may have been changing a setting that may have caused the initial issue, but if this continues you might try to contact the Samsung customer service center in your region.
Here's a snippet from the U.S. manual:
Could somebody tell me if the light at the bottom of the screen is supposed to glow all the time? Unpacked my new tv yesterday and it was on all day but this morning it wasn't glowing,but was flashing when ever i used the remote. I turned the tv off and on again and its back on? Could someone explain please x x x Does it go into standby or something and turn itself off. I had the back light set to 5.