There's no moisture-related reason to be concerned here, because moisture should never get to that area... unless, maybe, you have a full bullnose on the countertop edge, which would cause spills to run right around to the area you're concerned about. I'm assuming you don't have bullnose countertops.

A 1/4" gap is rather large. If you can see it easily and it bothers you aesthetically, you might ask about either caulking with an appropriate color or adding a small molding to cover the gap.