Airbag light on after a head gasket job

Completed a head gasket job and everything is running smoothly for the past few weeks; nothing is weird or off. But noticed my little red airbag light is on. I am pretty sure it was not on before the job, but I can't be 100% sure.

How can I check the system to see if it's just a sensor that is badly plugged or if something is really wrong with my airbag?

In case it impacts anything, the battery was changed during the head gasket job as well.

Thanks a bunch