Airbag light has dim glow when car is off? HELP!!!

hey i got home today from about a 3 mile drive and turned the truck completly off key out and all. i was on the phone so i sat in the truck for a few minutes then notices my scangauge flicker on and off real fast and then the airbag light that is in the dash start to faintly glow without the key in or anything...what could this be i am worried my battery will eventually die and hate when stuff like this is messing up...thanks

 

oh and new discovery. i went outside and the deash airbag light was still faintly gloing/pusling. with everything of i just unplugged the scangauge and the light completely shut off. why would this be happening?