Do you really think really Buddy's cares?
Not all of my Detroit style of pizzas bake exactly like I want them to. You can see the hole on top of the one pizza I posted. I am still learning about Detroit-style of pizzas too.
I'm guessing that you just had an air pocket that filled with steam and expanded when you baked the pie. One sees the same thing in the crusts of NY pizzas from time to time. Sometimes the bubbles will expand in from the rim and displace some of the cheese and sauce.
As for the "Detroit Style Certification": kudos to Shawn (or whomever) for coming up with a clever (and if it works, lucrative) way to make a buck, but he should just offer classes. The Keste folks offer a course in Italian-style wood fired pizza making in NJ that costs even more than $3,000 (I don't remember the exact number.
And he can offer certification for his personal method, but a certification in the "Detroit style" seems a bit of a conceit. Not that it's a bad idea, but a committee of recognized experts in the style - Shawn, plus, say, folks from Buddy's, Shield's, Cloverleaf, etc., should get together, discuss, decide, vote, and agree on a common Detroit style. In which case, I suspect that Buddy's would not go along with the requirement that the pies be baked in a deck oven.
And isn't interesting - amazing coincidence, I'm sure - that a guy who is a major, if not the major, source of the blue steel pans is making using these pans a requirement for the certification?
In my opinion, the style should be defined by the pie itself, not how it is baked: Light, airy crust, crispy bottom, cheese out to the sides and caramelized, pepperoni under the cheese, sauce on top (and the sauce can be put on at any stage in the process, since different, equally authentic bakers do it different ways.
And as the VPN specifications for "true" Neopolitan pizza do, the specifications must contain at least one very specific recipe, to include all ingredients, the exact proportions and the entire process from mixing the dough to baking the pie, including baking temperature. There must be specifications for the sauce, too, and there needs to be agreement on the cheese. And only a certain amount of variation, if any, should be allowed. So maybe a committee would be better, if Shawn want to keep his recipe secret, but his recipe, and everyone else's as well, need to be reasonably close to the published specifications or they, themselves, cannot be "certified."
And which, I suspect, could make a true certification regime impossible. The recipe for VPN Italian pizza is a common recipe, hundreds of years old, and pretty much public knowledge. But the DS style guys seem to want to keep their recipes - dough, sauce and cheese - proprietary.
So, probably the best one can do is, "baked in a pan, cheese out to the sides and caramelized." If one wants to pay $3,000 for that, fine. But I think it would be much better for Shawn to offer certification in the "Shawn Randazzo method." And for $3,000, it better be the precise recipe and method that he uses himself - that's what I would expect for $3,000.