Although I was very confident with Michie from Seeking Imperfection's husband's answer to my blue-ish green garlic situation but I decided to due a little research when everyone was sleeping last night and here is what I came up with....
From What's Cooking America -
Garlic is known to contain sulfur compounds which can react with minute traces of copper to form copper sulfate, a blue or blue-green compound. The amount of copper needed for this reaction is very small and is frequently found in normal water supplies. Raw garlic contains an enzyme that if not inactivated by heating reacts with sulfur (in the garlic) and copper (from water or utensils) to form blue copper sulfate. The garlic is still safe to eat.
If fresh garlic is picked before it is fully mature and hasn't been properly dried, it can turn and iridescent blue or green color when in the presence of an acid (the vinegar that was used in the recipe).
Are you using table salt instead of kosher or canning salt? That can cause the garlic to turn blue or green. Table salt contains iodine, which discolors whatever you're pickling. Use kosher or pickling salt. (I wasn't pickling anything but I did use table salt).
Don't worry, greenish-blue color changes aren't harmful and your garlic is still safe to eat. (unless you see other signs of spoilage).
P.S. The barbecued pulled pork recipe was delicious so I recommend trying it. My 4 year old ate a whole sandwich on a kaiser roll and you must note that he does not like "sandwiches". The next time I make it I will be using powdered garlic though!!