one plus one shows the 'charging' notification even when removed from charge

I bought the phone 2 weeks ago. there is no problem except this. when I remove the phone from charging the notification light turns off, but the lock screen keeps showing 'charging' message, after unlocking it goes away. Also if I restart the phone this gets solved but next time when I charge the phone and remove it after charging, the problem comes back. It is not a big thing but it is surely a problem. any solutions pls?