It's quite normal that Lightroom represents the data slightly darker than what you see in the camera. That doesn't mean anything's "wrong" - remember that it's exactly the same sensor data, not one pixel has been differently exposed.
The issue is rather that the camera manufacturers stretch the data as far as they will go. A "brighter" image is always a selling argument when the customer is in the store.
Lightroom, on the other hand, is conservative. It doesn't try to sell anything, it just wants to represent the full sensor data.
I've seen this with every camera I have ever used with Lightoom, three or four Nikons and two Sony alphas. When you get to know the camera, you get a feel for how much exposure it's safe to give vs. the camera LCD.