UPDATE: Brought him to breeder who looked him over and opened up his mouth. There is NO sign of mucus, his mouth and throat is absolutely clear. Why his throat is distended is unclear. The breeder said that possibly it's either 1) the very earliest sign of RI or 2) a minor scratch from a prey animal. I've fed it only frozen-thawed. So the conclusion is inconclusive and watch the animal, maybe feed smaller prey for a while, and of course to remedy the cage situation.

Thank you for all your comments, both good and bad. I'll move my next thread to the boa section. The breeder also show me his parents and I guess the size isn't too bad. He is a really nice guy who took time from his day off to check out the animal, and his animals are high quality. I really like this little guy and as Starmon said maybe we were destined to be together.