Same problem here, with a brand new Nikon 3300.
I followed Anil's advice: I blew air into the SD card slot and the problem was solved.
However, to be honest, I'm very disappointed about this. It's either a product design or a manufacturing defect.
In any case, it's simply unacceptable. Nikon gets associated with poor quality.
Not to be offensive or anything, but this is a frequent problem. It has nothing to do with the quality. If something was actually wrong, blowing on it WOULD NOT FIX IT. If there was a bit of dust in-between the SD card contacts and the contacts in the camera-just enough to separate one of the pins-the card would not be read properly. I have carried my D3200 when I had one, and now D600 and D300 through sand and other environments and can tell you I have had the same problem myself. It's why those little air cans with compressed air exist, or alternatively the little rubber blowers to get dust and stuff off lenses. My D600 has had the problem 3 times that I can remember, and the D300 once (it uses Compact Flash, and the pin design is much harder to mess up). As long as you are pulling cards in and out of the camera and exposing the inside of that card slot to foreign materials, you are susceptible to the problem. Who knows, it could have been something that was on the SD card, which when you put it into the camera caused the issue, then when the card was removed and you blew inside it was enough to get it off the contacts...