I'm guessing it's his first time to a knockout spot? I remember doing some light sparring and getting hit flush with a pretty soft left hook, and felt dazed. But now I know what the feeling is like and you can sort of hide the look on your face till it passes. I'm guessing it's just a bit of an over-reaction, sort of like when you get winded for the first time and start gasping for air and panic takes over. At least it didn't happen in the bout, I think you'll just have to see if he is comfortable with it?