98 Ranger Air Bag Light

I just purcahsed a 98 Ford Ranger XLT. When I left the place that I bought it from, none of the panel lights were on. After about 10 miles of driving the air bag light started to blink and now just stays on. I've heard this could happen if the truck was in an accident previously. There is no indication that it was in an accident.
Any other reasons that the light may stay on??????? I just don't want to be driving down the road and have the airbag suddenly deploy. Ouch.