It's definitely not a small deal as the markings and externals are the main selling point of the VFC MP5s.
It's very strange that yours is missing the markings on the receiver. Every single VFC MP5 that I've seen has the markings there.
By the way, I hope you took a screenshot of the original page because they ninja-edited their photo on the product page:
Taken from this link:
http://www.airsoftglobal.com/shop/in...ducts_id=16951
Edit: here's the cached version, the photo with the right side of the receiver has markings!:
http://webcache.googleusercontent.co...&ct=clnk&gl=ca