Mercedes c250d Loose wing behind passenger side rear wheel

[roystonjennings]

My 1 year old 5500 miles Mercedes c250d has a slightly loose passenger side rear wing (immediately behind the wheel). It had its first year service this week and I questioned this compared to the same wing on the driver side, which is tight. After the service I was informed this is because of the exhaust system on the C250d and is normal?
Can anyone confirm this? Thanks