Try a different cable, if not then the socket is faulty and will need professional attention. Over time the fault will worsen so there's no point in leaving it.

You may still be covered by Nikon's two year warranty though, so check here for details. If not, then one advantage of buying a major brand name is that you generally get better customer service; it's not unknown for Nikon to offer free goodwill repairs (you pay shipping) on faults of this nature which may be due to poor materials or workmanship at the time of manufacturing. Contact Nikon in advance to politely tell them how disappointed you are after carefully selecting a premier brand and ask if they will agree to meet part or all of the repair costs. usually they'll reply in a positive manner, but warning you that if there's any evidence of clumsiness causing the fault then you'll have to pay.

I hope that my reply has been of assistance to you; please spare a moment to rate my answer.

Without delay go to the nikon service and ask to the needful