BillD. Here are your rerferences for RES spawning late in their 1st yr of life:
1. Wilbur, R,L.1969. The redear sunfish in Florida. Fla. Game Freshwater Fish Comm. Fish Bull. 5:1-64.
2. Brown H.W. 1951. Results of stocking largemouth bass and channel catfish in experimental Texas farm ponds. Trans. Am. Fish. Soc, 80:210-217.
Normally spawning occurs in the 2nd yr as you are see in your sources.
IMO Bob L has the best guess. These are offspring of the HBG who can grow and mature quickly at small sizes.
Thanks Bill!
I haven't found those actual papers yet but I have found many others that refer to them. Thanks so much for digging them up!