My son caught another one today, same exact place, but about 1" smaller. The shape and colors were exactly the same, but it had banded stripes much more like a bluegill than a pumpkinseed.
Hybrids are pretty rare in these parts, maybe 2% of the Lepomis population by my guess, so possibly the 2 were from the same spawn. I'm changing my guess to Green x Bluegill.