Was this by any chance the Zorua you got from Rood?
Because if it was, this is N's Pokemon. A Pokemon with perfect IVs. Something incredibly, incredibly rare to appear in any Pokemon. N's Pokemon can appear all over the place in Black 2 and White 2 with the help of the Memory Link, as they were released by N. They all have a set nature, and a set level - everything is set. Plus, since N once had these Pokemon, the Pokemon are treated as traded Pokemon. Meaning, they get boosted experience.
This is a good thing! Don't worry!
Hope I helped. :)