When it's happening, do you have anything at all in the passenger seat? Oftentimes it will sense weight that is close to the limit and the shifting cargo while you bounce and turn will make it think you're cycling between under and over the weight limit to enable and disable the passenger airbag. If it's happening with nothing in the seat, then definitely get it in the shop. If you have some, but light weight, it's designed to assume that it's a small passenger who would possibly be injured by an airbag, so it disables and the light lets you know. Sometimes a backpack or similar will cause the same effect.