Good news, I guess. It turns out that it's a Gelcoat Blister that is covered by the 5-year hull warranty. It's the biggest blister the dealer has seen yet. Glad I can be the "winner" of that award. They said that these blisters usually show up in the first year of ownership. I feel good knowing that I didn't do that to the boat. Thanks for everybody's help!
I have not crawled into the boat to see. I'm afraid this is too far back to be accessible from the ski locker and too far forward to be accessible from the engine compartment. It might be behind the freshwater tank. Interestingly, if you tap around the boat, you can find similar spots, most are much smaller (like an inch or two in size) around the boat.