Why is my Kabuto from an egg shiny?

I just happen to get a random egg, it hatched into a Kabuto, but it was green and it sparkles, then because of the sparkles, I knew it was a shiny, is this supposed to be something new or a glitch, I got also got this 3 star egg all the sudden the next day, the other one hatched into an Aerodactyl but it was normal,
Here are my questions:

  1. Is this supposed to be a glitch or not?
  2. Is this egg hacked?
    3…If this is not hacked and not a glitch, what are the chances of getting these shinies?
    Here is the image of Shiny Kabutops:

Certain Egg Pokemon do have a chance to be shiny, Kabuto included.