Our 2012 Passat did the same thing when it was new. It eventually went away and the level never went down anymore. No sign of a leak anywhere, so we chocked it up to the hoses expanding or something like that.
If you don't have to add more than a few ounces of fluid to bring it back up to normal, I wouldn't worry about it. If you see a leak or you have to add fluid more than once, start looking deeper.