Depends on the load and application you are running on it. For light loads (browsing, Netflix, videos, etc.), the fans aren't audible. If I am not mistaken, all 3 models of the Macbook Pros (13" nTB, 13" TB, and 15") never turn off its fans, but is extremely quiet at idle to not be audible in normal circumstances. For example my 15" under light loads spin its fans at 2,000 RPM, but it's never audible at that speed.
I would say don't worry about it unless you are running heavy loads and the fans are still not noticeable.