Airbag Light Question.......

I have a 1997 Kia Sportage 4WD. When you first start it the airbag light comes on and stays on for about 3 or 4 minutes before turning off. It doesn't blink and it doesn't come back on while driving. I realize it is supposed to come on momentarily during and after startup but shouldn't it turn off after 5 seconds? Is this a sign of a problem with the airbag system? Is there a timer I can adjust or replace? Or is this normal for a Kia? Any help would be appreciated.