No strange behavior before/during/after. He has remained the same as prior to this issue. He eats religiously and is defecating/urinating regularly.
The rats were being thawed in tepid - warm water until fully thawed, then heated with hot water/heat lamp for about 30 seconds to bring them up to temp. He has since been switched to live large pups or weans from my own rat colony (per vet recommendation). The first feeding after switching, he did swell after feeding. Though his next feeding he did not, so I'm not sure if the first time was a result of feeding or a result of the seemingly random swelling.
Edit: As far as activity level, he is doing normal ball python style behavior. Hiding most of the day but switching hides from hot to cool normally, more active at night, and very active/tub cruising come feeding day. When handling him for his swelling exercise he is exploring/climbing without issue. Not flailing or staying balled. I can touch the swollen area without much reaction. If I go for it directly, he pulls his head, but if I slowly come from behind he doesn't pull back from pain etc. So I would say that's rather normal BP reaction.