We just completed a kitchen remodel and have newly installed granite counter tops. The sink is a drop in model (swanstone). With the way things ended up, there is approximately a 1/2" gap between the back edge of the sink and the granite backsplash. This is going to be an obvious area of problems with water, cleanup, etc being so thin.

I think I would like to seal it so water can't just sit there and cause problems. Is caulk the best answer? Should a backer rod be used? The approximate lip height of the sink is 3/8".

Thoughts? Recommendations?