I'd tape both sides of the joint and use an unsanded color-matched grout or clear grout - really squish it into the joint - smooth it, and remove the tape. There is also a runny crack sealant for these spots. I don't remember the name of it, but my tile guys used it in a couple of spots.

Hello Kathy and Rainey, The caulk should be applied at all of the changes of plane. The caulk will then act as an expansion joint to prevent pressure from expanding and contracting structure from adversely affecting your tile and grout. Because most backsplashes are cosmetic, it's not very important if your contractor eliminated this step as a caulked joint can often be more conspicuous than a light crack where the slab and tile meet. Shaughnn

Looking at the pics and description, I'm assuming its the two 4 inch LONG grout lines visible in the pic. I'm also assuming that the previous posters are assuming a 4 inch WIDE grout line, which would not make sense :)

I talked to our installer and we will be doing the 100% silicone product in all of the change of plane grout lines. I figure it is better to have it look a little shiny and have the functionality I need. I was just curious how it looked. Do you think we should dig out the grout on the floor butting up to the alcove tub and shower curb? I don't anticipate those being extremely wet areas, but I am not sure if we pay to do that or not.