It was one exam. I wouldn't think too much about it.
Try one more exam and see where your mark really is... If your mark stays consistent in the 460 region. Then just focus on the subjects which you are getting lower performance in... Try to use those score reports the nbme makes as best as you can.. If you do enough exams, you will start to see the range of marks your most likely to get on the USMLE. But hey, a 214> is defintelly very good to start off with.. Your already prepared to do well on this exam.. Its just a question now as to how high you will get.