Generally, the riser at the back of a free standing range goes up against the wall - though there may be a gap of a 1/2 inch or less. A slide in ranges would have a gap - but that is because they are designed to slide in up to the back of the countertop. Have your builder check to make sure he routed the electric and gas hookups so they aren't keeping the range from sliding back completely. I am not familiar with your range, but most manufacturers specify particular places where the electric outlet and gas pipe must be located so the range can slide in flush to the rear wall.

Thanks, BarryV. Is it a major issue to move the gas and/or electric connections? I'm trying to decide the best way to handle this with our builder. He has another potential solution with a piece that Electrolux sells. He would remove the 6" stainless backsplash and change it out with a piece that comes up lower, but extends out to the wall in order to cover the gap.

It is pretty easy to move an electric outlet, gas is a little harder, but both can be done. I checked the installation instructions for the dual fuel and it shows a decent sized area to locate the electric outlet - but does not show where they want the gas outlet - I guess it is supposed to be at floor level - but can't say for sure. Does he say it can't be fixed by moving the electric or gas connections? I can understand his situation since the installation instructions don't clearly show where the manufacturer recommends the gas ( page 4 and figures 4- 6 show exactly where they want the electric outlet) and many manufacturers spell it out very specifically so the builder doesn't have to wait until the appliance is on site to figure out where to run the connections.

Here is a link that might be useful: installation guide