Glad to hear he's eating & gaining weight for you. Most of us realize how hard it is to get some snakes to take f/t prey; I hope you'll try again at some point in the future, for his safety, but for now it's best he gain weight & strength anyway. (It's been a while but I recall he was thin, & for a young snake, health takes precedence.) It's also fortunate that handling isn't bothering him prior to feeding him- some snakes it does, & others not so much, so when advising you here, all we can do is speculate- offer you possible explanations- because we're not actually seeing him & spending time with him as you are.