Didn't do a thing and the airbag light is on.

[Summerfun]

1999
Boxster
90k miles.

I read that people take out seats,airbags and such and the light goes on but I did nothing but turn my car on.
Am I going to have a problem with my bag?
I also read about seat belt sensors going bad over and over.
Can I clean something,tighten something? I don't want the nightmares of people replacing seat belt parts over and over.
Could a battery losing cranking amps set it off? My car starts on the first turn but it sound like it's taking a lot out of the battery.
I already ordered the durametrics kit but down the line if I want to sell my Boxster for a newer one then people will look at it like it's damaged goods that can't pass inspection and haggle me down. Help!

p.s. What's that countdown on the dash with an oil sign.Is it a countdown to an oil change?
thanks for any answers in advanced.
Richard.