Stanton floor

A question for any Stanton owners out there. Mine was registered this year 2016 when I bought it but I believe it was probably manufactured in late 2014. There is a ridge in the floor which you can feel through the carpet. It runs across the van floor approximately from where the wardrobe & toilet compartment meet towards the fridge on the other side. Is this usual? I remember feeling it being there when viewing the van at the dealers. The only thing I can think is it is where the rear floor is strengthened as the chassis does not extend to the rear of the van. In other words the floor is strengthened as its unsupported for the last 0.75m. It's not uncommon to have an unsupported rear section - a previous Auto-trail I owned had its rear bathroom totally unsupported. Any thoughts?